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Two year update on BBK here in Thailand...

Joined
Jul 15, 2022
Messages
18
Let's call this page 1 of the El' Diablo build:

It has now been a full two years since I had the iTimgarage BBK installed on my Honda CT. Myself and the two guys I ride with have now gotten all three of the little CT's lined out and running rings around those stock CT's here. I do have a YouTube channel documenting our rides in the mountain areas around Chiang Mai, I'm sure many of you have seen some of my videos and are subscribers and I appreciate your loyalty, so thank you very much. But this is not about my YouTube channel, it is to give an update on two years of the BBK from the initial build to what problems we ran into and what was needed to fix them... My bike aka, El' Diablo was the original guinea pig as I've been riding and racing since 1969 and even ran my own race team. You may or may not have heard of it, "Team DNF Racing". We started our team in Wyoming and raced enduros in Colorado RMEC in the early 80's. A move from Wyoming to my home state of Oklahoma and starting a team on race quads we did prep work for four different teams of riders in the last 12 Hours of ATV America held in Texas 2007. All four of our teams made the podium in their respective classes. We had a Youth team, 3rd in class, a B team, 1st in class, an Ironman entrant, 1st in class and an Industry class team, 3rd in class. We prepped the machines for events, we didn't do extensive engine work, but worked mainly on suspension and maintenance on the race machines. Contrary to our teams name, we very seldom had a DNF in a race. Prior to making the move from Wyoming to Oklahoma, I was a certified mechanic in a Chevrolet dealership for 15 years, that is where my mechanical background comes from. Now that my age has gotten up there, my memory isn't what it used to be, so naturally, I do forget things from all those years long ago. So, enough with my history, here is how the BBK got started on my Honda CT125.

After buying my Honda CT125, some friends we know here in Thailand rode bikes through out Northern Thailand and asked if I wanted to join them on a ride to Chiang Doa which is in the mountainous area North of Chiang Mai. I was eager to see what the little CT would do, so I jumped on board. I spent the entire day following way behind these guys and constantly having to shift down to 1st gear and then revving it out to try and carry 2nd gear up some of these roads.... The little bike is pathetically weak in the power category and this ride alone taught me that. After being passed going up hill by a Honda Wave 125i with two up on the saddle, I knew I had to start looking for a way to add a few more HP to the extremely weak 8 HP that Honda had so generously given my bike.... This folks is how I started to explore the possibilities of getting more POWER out of my bike.... This is also the start of how El' Diablo was transformed from a mild mannered, weak putt putt, to the dragster thumping sound it has today. I'll write more later, as right now, my wife has a Honey Do for me and I better get started on that....
 
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Joined
Jul 15, 2022
Messages
18
Let's call this page 2 of the El' Diablo build:

Okay, I've gotten most of the Honey Do's done for my wife, and I'm eager to continue the rise of El' Diablo. After a really bad ride with my friends here in Thailand where I was left behind during the entire ride, I decided I either needed to buy a bigger bike, or make this bike do what I really wanted to do with it. For one, I'm a dirt bike guy, I started on dirt bikes, I've had dirt bikes almost all of my life from the age of 16 till, well lets not say how old I really am, but 70 is around the corner. So, I've owned road bikes, I've not really enjoyed the road scene as much as the dirt scene, but I have had my share of pavement only bikes and that really is what these guys wanted to do. So, I either get more ponies out of my CT or I get a bigger road oriented bike. So I got on the internet and started to search. Seems here in Thailand, they have been making the little four stroke engines perform very well for some time. I found several BBK's available and I researched them all before settling on the one from iTimgarage. It appeared to have an all inclusive setup with a larger fuel injector, a piston from the Art manufacturing company and a stock Honda cylinder that was bored out to accept the Kawasaki Z-50 stock sleeve. Now, I did the research and Art pistons where a company founded by Hirohito Honda, yes, the same Mr. Honda that founded the Honda motorcycle company. So, it seemed to me, all of the parts used for this BBK were of quality engineered. I was not wrong, we have had absolutely no, and I do mean no, problems with any of the components in the iTimgarage BBK. The fuel injector came from a Honda PCX 150, seems right as we were asking for fuel for about that cc's. However, there did creep up a problem that I did not foresee and it should have been an easy problem to solve if I had just used my knowledge from my days as a mechanic. We developed a pre-ignition knock on two of the three bikes. Mine did not do it and I'll let you know later why mine didn't do it. Daniels bike had the issue first, it got extremely hot on a ride up the "Hells Trails" and developed a severe pre-ignition knock that I miss diagnosed as a rod knock. Once getting the machine down from the heights of the mountain and on level ground in Chiang Mai, it did not do the knocking noise. We even stopped at a certified Honda dealer and he could not get the bike to make the noise. I was baffled until I found out that the day before our ride, Daniel had taken the bike into a "Cub House" dealer and they adjusted the valves for him. Now, I'm assuming that they got the exhaust valve to tight and that was causing the engine to over heat and hence the knocking noise. We had my mechanic replace the BBK with a new one and upon inspection of the original BBK, he found nothing wrong. This had me stumped, I asked him about the valve adjustment and he said they were spot on. Shit, now I'm really beside myself on what is causing this problem. About time to give you guys a break and let me continue the process later. I promise to tell the entire story here in just a few days, so give me a chance to tell the whole ordeal before you start the questions and that way I can answer everything at once.....
 
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Joined
Jul 15, 2022
Messages
18
Let's call this page 3 of the El' Diablo build:

After my mechanic whom I trust and here is why. Way back about 9 years ago, I was looking for a bike repair guy to do my normal service work on my 2013 Honda Wave 125i. This guy had an open air shop (which most shops are, they set right on a roadway out of a little one stall garage) and I stopped in there to see if he could do an oil change and overall maintenance work on my bike. At this time, I'd only been in country a short time and had absolutely no tools whatsoever. He was at the time working on a Honda Cub. As I watched him, I'm seeing what looked like a very small turbo being installed on this bike. It was and what that bike did, told me that I had found the guy to do my work on any bike I would have while living in Thailand. It literally screamed down the rode. I mean I've never seen any small bike like that, two stroke or four that would accelerate like that and the sound was so awesome..... Yep, this is the guy who is going to take care of any bike I get here in Thailand. Just so happens, he is part of a group of ten guys who each have a special trade in making small engines perform to their optimum. What a lucky deal for me and yes, this was 9 years ago..... Since that time, he has been my go to guy for any mechanical work on any of my bikes I've had. Yea, I've had a few since then and he has taken care of all of them. Sooooo, after Daniels bike did this, we took it to my mechanic to check it out, I had the stock Honda parts from Daniels bike he had swapped out for the BBK and I also had another new BBK. I was there when he did the tear down and we both inspected the parts, nothing, maybe a small knick on the piston that could have been from an over tightened exhaust valve, but nothing else said the bike should have had that knocking sound. I had him install the new BBK and told Daniel to slap a 1,000 Kilometers on it before we took it into anything difficult. Meanwhile, Robert was observing everything we were doing and decided he wanted to try the BBK as he was tired of paddling up hills when we went for a ride off-road. I didn't blame him, I'd of opted for the BBK a lot quicker than he did. While Daniel is putting more Kilometers on his bike to get a good break-in done, Robert and I were trying new trails out. During this time, Robert was starting to experience the same issues as Daniel had with the pre-ignition knocking noise, only not as bad as what Daniel had. Now, I'm really getting confused about this and I'm still not having any problems with my bike with the knocking noise. But, I am starting to burn oil and I'm having a back firing issue. I've decided that the burning oil issue is from them possibly causing it when they did the BBK by messing up one of the valve stem seals. The back firing problem should be able to be fixed with the ECU being re-tuned more precise. I took El' Diablo back to my mechanic and I showed him what I thought was wrong, he seemed to know what I was talking about like he might have maybe messed up one of the valve stem seals when he did the BBK. A day later, I got a video message from him showing my bikes head and cylinder with him pointing at them and saying something in Thai. I don't understand Thai very much so I had Robert translate for me the best he could. He said something about the mechanic saying "They don't match". I didn't know what he meant, but he did show me the broken valve stem horn where the valve stem seal is attached, so I gave him a double thumbs up.... Evidently, what I had done was give him the okay to install the hot cam, port the entire head and have the ECU re-mapped. I was a little shocked that it cost what it cost, but now I have El' Diablo in the form it is today. When I gave him the double thumbs up, I guess I gave him the okay to port the combustion chamber, the exhaust chamber, the fuel injector chamber and the Throttle body chamber and the throttle body itself. What I'm saying is they not only lowered my compression on the engine by porting the combustion chamber to about what was stock for compression, they also gave me a lager exhaust port, a larger fuel port, a larger air intake port and they modified the throttle valve assembly. They could have replaced the throttle valve, but for them, porting out the inside and putting in a larger valve was what they do. I can't complain, it works great. When I got the bike back, it didn't burn oil, it very seldom would backfire, but more importantly, it would set at idle in gear and hunt like a dragster on the starting line of a National Drag Race. Yes, my bike hunts, and then it accelerates like the bike Honda should have made for the general public. More later, I'll let you know what the subscribers have said about El' Diablo when they got to ride it..... No, it's not for sale, no, I'll never get rid of it. Yes, I have purchased my new bike for 2023...... If you want to see what that is, watch my YouTube channel: Lazy Dog Productions
 
Joined
Jul 15, 2022
Messages
18
Let's call this page 4 of the El' Diablo build:


After the extra work on El' Diablo to have the oil burning and back firing taken care of. Both Daniel and Robert were very impressed with how much more power my bike had than theirs and they both still had the pre-ignition knocking noise. I call it the pre-ignition knock because that is what it was, I just had not pin-pointed it as of yet. It was about this time that Robert took his bike into iTimgarage to see what they could do about the knocking noise. They immediately understood that problem as there were multiple Honda Wave 125i riders who had the BBK installed that had the same issue. This is where all of my mechanical training an knowledge got turned upside down. Here is how I found out what they had told Robert. We were doing an intro to a ride and he said he was also doing a test on the BBK's knocking noise by lowering his octane rating because iTimgarage said that it had helped about half of the Honda Wave 125i riders who had installed the BBK. This is during our intro to a video, I was standing there wide mouthed and in awe of what he was saying as this is just backwards to anything I had ever learned about high compression engines. If it truly was a pre-ignition knock, then we needed to raise the octane to compensate for the higher compression caused by making a larger piston in the same combustion chamber as the stock CT 125 had. Now, it was all coming back to me. I let it go and he had started to use a lower octane gas and maybe because we didn't go on as severe trails, his bike didn't knock like it did before. Prior to this, I had told Daniel to start using Benzine gasoline in his bike as that has the highest octane rating we can get here in Thailand. It is the same fuel I use and have always use in my bike which is why mine probably never developed the pre-ignition knock. However, I had the porting job done on my head and never came close to pre-ignition knocking noise, that and I always ran as high an octane gas as I could get. This is when I realized that the knock they had was caused by high compression and to low of octane gas to compensate for the higher compression that we caused by installing a BBK. Robert was the first to go ahead and have his head ported, a hot cam installed and the Honda Wave 125i ECU installed and re-mapped for performance. Once that worked for him, Daniel followed suit and now we have three powerful and well built BBK bikes that perform flawlessly for us. Since the porting of the head, which is all we needed to do to make the BBK work without any problems we have had excellent performance from all three bikes. We have now had multiple subscribers from our YouTube channel come to Thailand to visit us and to ride one of the bikes with the BBK. It seems that El' Diablo is a must ride and those who have had the privilege to twist that right side grip and feel the power that Honda should have put in this bike from the start, are very glad they got the opportunity to ride the legend. This past week, two more of our subscribers who bought new Honda CT's moved to Chiang Mai, Thailand and are going to be joining our little group to do adventure rides in Thailand. They both got a chance to throw a leg over El' Diablo and both want that same power in their bikes. Problem is, there bike have the new Dax engine in them and I'm still searching for a BBK to install in those two bikes. I won't give up until we get what they want. A BBK for the 2023 Honda CT125...... I hope you like this little story about how we developed the Thailand Honda CT 143. Now if you have any questions, post them below and I'll be glad to answer them.......

Eddie
 
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m in sc

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Feb 2, 2021
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still w the non-us market gen 1 interface ecms i assume? left (gen 1) vs right which is what we all got stuck with?

 

m in sc

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interesting. the one i have pictured is for a 22 grom but w the same basic interface as the us ct. the us ct one has less pins on the us model, some of where the brass tabs are are 'blank'. my guess is they are modding a grom ecm or its just completely different over there (not unusual).
 

tumblingdice54

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Mar 19, 2023
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On the Thai and Japanese after-market sites for CTs, there are quite a number of 143 and 181 big bore upgrade kits. Any idea which ones are best buys for a 23 CT? Mine is being delivered shortly and I really want to get it upgraded over the winter. Thanks a bunch. Really enjoy all your videos!
 
Joined
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On the Thai and Japanese after-market sites for CTs, there are quite a number of 143 and 181 big bore upgrade kits. Any idea which ones are best buys for a 23 CT? Mine is being delivered shortly and I really want to get it upgraded over the winter. Thanks a bunch. Really enjoy all your videos!

I'll give you an answer on this but you probably won't like it. First, I've stopped posting on this site because what is available here in Thailand and what is available in the US seems like they are two different motorcycles. What I mean by that is what is in the electronics, mechanical and somewhat cosmetic appearances are different from the two countries. I can only report on what is available here in Thailand and yes, we have done some very intricate experiments with the Gen 1 and the Gen 2 Honda CT 125's. Here in this country, your model year is set from the manufacturers build date, not a specific model year by improvements and such. My CT is a model 2020 because it was built in 2020 even though the production line would label those bikes in the US as a 2021 model. So for future identifications of the Honda CT 125, I will use Gen 1 and Gen 2 models. There are 2022 model Gen 2 bikes here in Thailand and we now have three of them in our ride group. We have also tried to improve the power output of these bikes. Currently it is very difficult to find "ANY" improvements to the Gen 2 engine. The reason being, it is a Dax engine copy, not identical, but an engine copy with minor differences that keeps "you and me" from changing out items from the Dax to fit the CT Gen 2 engine. As of now, we are working with a shop to get an exhaust pipe built to improve performance of the Gen 2 bike. Once one is complete and to their specs, we will get one to try on a Gen 2 bike. The only other item we have been able to make fit and improve performance is a 42T rear sprocket off a Honda Wave 125i installed on the rear wheel "which is still identical to a Honda Wave 125i sprocket bolt pattern". Good luck trying to replace the countershaft sprocket. It appears that Honda doesn't want you to change that out. As for a BBK for the Gen 2 engine, there is not one available here in Thailand. Not what you wanted to hear I'm sure, but I'm sure there is a shop somewhere here in Thailand that is working on a kit for the Gen 2 Honda CT 125 engine, but I have not heard of one. The Dax and CT125 bikes are not that popular here, so engine hop-up kits are not being experimented with like the more popular engine designs like the Honda Wave 125i. So, to answer your question, there is currently no 143cc, 162cc or 181cc Big Bore Kits available for the Honda CT 125 Gen 2 bikes here in Thailand. Read back through all the posts on this topic, there is a member that says there is a kit available by a Japanese company. I'd say buyer be ware on purchasing that kit, I have heard of no CT Gen 2 owners who have one on their bike. Good luck, let me know what you find out there......
 
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dmonkey

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Wayne at The Speed Shop in Georgia has done a USA 2023 CT125 JA65 build with a 149cc DHM big bore kit.
The new Euro-5 engine has a different stroke and stock bore so the BBKs work out to different dimensions than the ones that are common on the older engine. The closer proximity of the head studs on the new engine also limits how large of a cylinder can be run, the larger displacements are likely off the table because of that.
 
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The new Euro-5 engine has a different stroke and stock bore so the BBKs work out to different dimensions than the ones that are common on the older engine. The closer proximity of the head studs on the new engine also limits how large of a cylinder can be run, the larger displacements are likely off the table because of that.

I am very much aware of this and until I have a chance to tear an engine down and see what can be done, I'm under the same impression, as of right now, there is no viable Big Bore Kit for that engine. Just so you all know, here in Thailand, a Gen 1 complete engine for the CT 125 is not that expensive. We may just go that route just so we can get the three Gen 2 bikes in our group up to what we have with the other three bikes. It's totally up to the owners of these bikes, not me.....
 

dmonkey

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@Lazy Dog Productions Do you happen to have any photos illustrating the countershaft sprocket incompatibility? I ask because I'm seeing that folks in Japan with the JA65 (Gen 2) are running the same aftermarket sprockets (e.g. this Kitaco one) that fit the JA55 (Gen 1) and the parts fiches I can find list the same fixing plate implying that the splines would be the same, though the sprocket may still be a different thickness or offset. P/N: 23802-GN5-910
 

dmonkey

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Kitaco just announced they're coming out with a 145cc big bore kit for the new engine as well:
 
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Do you happen to have any photos illustrating the countershaft sprocket incompatibility? I ask because I'm seeing that folks in Japan with the JA65 (Gen 2) are running the same aftermarket sprockets (e.g. this Kitaco one) that fit the JA55 (Gen 1) and the parts fiches I can find list the same fixing plate implying that the splines would be the same, though the sprocket may still be a different thickness or offset. P/N: 23802-GN5-910

We tried Dax engined sprockets, didn't work. We tried them with the Gen 1 sprockets, didn't work. We tried them with the fixing plate, didn't work. What we found was the spline on the Gen 2 CT bikes were tapered and the Gen 1 engine sprockets would not slide on them. We tried Dax engined sprockets which will slide on, but if the sprocket would slide on, then the fixing plate would not line up with the holes in the sprocket, so we got a Dax fixing plate, the fixing plate won't line up with the splines. After trying everything available here, (No Honda Dealer had a 13T countershaft sprocket for the Gen 2CT, only available in 14T) we went with the rear 42T sprocket from a Honda Wave 125i. This change also requires a longer chain to be used, but sprockets for the Honda Wave 125i are plentiful and Honda still uses the same rear bolt pattern for both the CT Gen 1, Gen 2 and Wave 125i. There was a very noticeable improvement in low end power with a minimum amount of top end speed loss. As for the BBK, buy one and put it on, if it works let everyone know, if it doesn't, again let everyone know. As of now here in Thailand, there are no BBK's available for the Gen 2 engined CT 125.......
 
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