HONDA CT125 Big Bore Kit

[m in sc]

we'll see. would be nice and id be in on that, but im not wasting time at a dyno hoping its tuned right, auto tune and real time feedback is where its at in the real world.

 

[Lazy Dog Productions]

Wow! You all jumped on this quickly. First off, I was very skeptical about the Octane issue when the mechanic at iTimgarage suggested dropping down in Octane to try and solve the engine knocking. If any of you have had an older car with a carburetor and a big engine, I'm sure if you played around with the timing on it, at one time or another you developed and engine knock. Cause of the knock, the timing of the compression with spark from the plug is off far enough to cause a knocking noise. My thinking on this was just the opposite of what iTimgarage told us to try. I thought we needed the highest Octane fuel we could get to achieve the best power to Bang ratio. Here is what we found out. With the higher Octane and the much higher compression we now had with the BBK installed, and with the engine getting hotter with stress, it was actually causing the combustion to ignite before the correct timing was achieved. Hence the knock. I personally didn't believe this until Robert started to use lower Octane fuel to test the theory. Sure enough, in the same trails with the same riding conditions, he actually had less knocking noise with the lower Octane. So, with the port job on the combustion chamber on the stock head, it lowered the compression and the knock went away even with higher Octane fuel.... This is an issue that we have been working on for a year now and it seems to have fixed the problem. iTimgarage also said that the locals that installed the very same BBK on their Honda Wave 125i were also having troubles with the engine knock and for most of them, the lower Octane solved the knocking problem. Those that it didn't, went straight to a port job and that fixed it with the lower compression. There was no need to install a different ECU to the Honda Wave 125i as the one we used on Roberts bike was from a new model Honda Wave 125i. I'm glad to see you all kicking this around and it is a shame that you can't get some of the stuff we can get here in Thailand. I know I'm very lucky to have access to shops that have diagnostic equipment that I would never be able to purchase and that they are eager to hook your machine up on those pieces of equipment and show you the results. The cost is so ridiculously cheap here it is not funny. Like I said in one of my earlier posts, they have had this engine design here for over 50 years and there are some pretty sharp individuals who have worked extremely hard to come up with what works to make this engine design sing a different tune. I'm very happy with my engine mods and I had a small group of bike-nerds do all the work. I will be talking with one of them soon and get the part names of everything they installed and any of the mods they did with a drimel. I'm like most of you, I need to do some more research to verify why the Octane made a difference, it goes against everything I was taught as a mechanic.....

 

[SLO]

Yeah, against everything I understand on compression and octane? Maybe a distraction to then have you return for the larger service?

Translated several times,the info is always lost. Higher compression requires higher octane to prevent pre ignition.( knocking )

 

[Motoboogie]

Yep, Higher octane is more stable which helps with pre-ignition on high compression engines.

A lot of folks think higher octane makes their car/bike faster, but it has nothing to do with that.

 

[AZ7000']

I agree with both of the above, hence the confusion that lower octane on a higher compression BBK would help the engine knock. I'm at altitude and the pumps are generally lower in octane then down the hill in Phoenix.

 

[m in sc]

the reduction of compression fixed the pre-detonation, its that simple. I don't care what they said about curing it with lower octane... , science disagrees. Timing, combustion chamber volume, and valve overlap are pretty much all that controls compression. typically, as long as the timing is optimized, you can run RON rated 87 up to about 9:1, on my big block dinosaur built galaxie with 10:5 to 1, i run 93 and 36 degrees total timing. the rules are all the same on 4t motors, regardless if its a 125 or a 6+ liter.

 

[Lazy Dog Productions]

I did some more research as like I stated above, the lower Octane fix was against everything I have ever learned about engines. Here is what I've discovered. As you all know, the gas/air mixture entering the combustion chamber actually cools the combustion chamber down. If for some reason, the chamber is not cooled down enough, it will ignite the gas/air mixture prematurely and this causes an engine knock. All higher Octane does for the engine is it helps stop this premature igniting of the fuel/air mixture and produces a bigger bang, hence more heat. It could be that the Thai thinking on this is to reduce the Octane to reduce the heat of the combustion chamber. I don't agree with this, but this could be why they suggest lowering the Octane. Remember when you could get gasoline with lead in it. The lead was there to stop engine knock. Well, we can still get leaded gasoline here in the form of Benzene. That is what I used in my bike before getting the port job on the head. That could very well be why my bike never had the engine knock while both Roberts and Daniels did have it. Lowering the compression fixed Roberts, now Daniel has set up to have the porting job done on his bike. Not all gas stations here in Thailand has Benzene available, but the station I use near my house has it and that is more likely to have kept my bike from having the knock. Here is where I believe Robert got bad info from iTimgarage. Robert speaks Thai, but not always uses the correct words. I think there is a possibility that he got "lower" and "higher" confused. I had been telling Daniel to use the Benzene in his bike but he said the stations around his place did not carry, so he used E91 gasoline in his bike. There is E95 also available here but again, the station he uses doesn't carry that. It's a Thai thing. These are some of the issues we have been having pertaining to the engine knock. I will talk with my wife this evening and ask here the Thai words for "lower" and "higher" and see if they could be mistaken for each other.... It could be that simple and I should have done some more research before posting the Octane message above. Sorry for that guys, as like I said, it went totally opposite of what I knew about engine knock. I even went so far as to talk with a Chemical Engineer from the oil company that I worked for and yes, gasoline will ignite with enough compression and enough heat without a spark. Again, this may be the Thai thinking on the issue for lowering the Octane, but I don't think it is. I will always use as high an Octane as I can get for my bike and I will suggest that Robert and Daniel do also...... I'll post more when I learn more, but I don't think lowering the Octane was the correct thing to do.....

 

[AZ7000']

Remember when you could get gasoline with lead in it.

Still can at the airport! 110 low lead, then I need to cut it and the only ethanol free around here, without an account is 91. (87 if you have an account with the fleet station, lower Oct up here at altitude)

I gave up as the old trail 90 didn’t like the higher resistance to detonation!

Thanks for the clarification

 

[RustyRodder]

This thread is pretty dang informative!

On the note of fuel- is anyone trying the (apparently new) takegawa fuel controller? Looks like they have a plug n play model now.

 

[m in sc]

This thread is pretty dang informative!

On the note of fuel- is anyone trying the (apparently new) takegawa fuel controller? Looks like they have a plug n play model now.

i have not. i reached out to hard racing about it, they 'said' it was unreliable, but im not sure why they felt this way. Not to thrilled about paying 500 bucks for something that doesnt auto tune either. I'll probably wait for a legit open ecu like th e1st gen groms could get. MY opinion is that the new bikes will run on the old ecm IF there was an adapter harness, all the important stuff is the same. I actually have an old grom wiring harness, i have been tempted more than once to retrofit it to the trail... and then its open season on engine management.

But the one you referenced is:

SP TAKEGAWA : FI-Con TYPE-e (Injection Controller) [05-04-0121]

 

[JPMcGraw]

This thread is pretty dang informative!

On the note of fuel- is anyone trying the (apparently new) takegawa fuel controller? Looks like they have a plug n play model now.

I got it when i bought a 143 kit. So far the tunes that come with it work but until i get my 14point7 wideband installed i won't know if they are safe tunes. Right now i have the tune for "Normal 125cc + CAM + Exhaust + Filter" and i can hit 60mph (speedometer) tucked on a flat. I rode it for about 12 miles at 55mph in 90* weather with no problems so its good enough for me for now. I also take my SO out looking at expensive neighborhoods and we hit 50mph regularly if only for a mile or so before we turn off. I haven't experienced any unreliability yet. This winter I'm putting the 143 cylinder and piston on and hooking up the wideband. The bike definitely has better acceleration above 5,000rpm and my top speed is higher but i think i have to play with timing to get a better top speed and the Takegawa only controls injector pulse width in microseconds. I'm not worried about top speed though, just maintaining speed up hill going over 45mph so I'm not a nuisance.

Right now my mods are:
-Takegawa S-CAM
-UNI pod filter
-Yoshi magnum GP exhaust
-Finbro Big Valve Head
-PCX injector

Is it worth the money?

¯\_(ツ)_/¯

I did enjoy taking everything apart and putting it all back together. I also broke some tabs on the body panels so that worry is out of the way now

 

[m in sc]

thats about the same performance (topend) i get out of mine with the eife, 143 and cam & exhaust. but it def gets there faster with the 143, and climbing long hills and ability to pass def better. i think what you're going to find is the top speed will be no better but the midrange and torque will be vastly improved w the bigger bore, on this bike. To the point if i shift spiritedly from 1 to 2 now, i can slip the centrifugal clutch.

 

[Jitenshakun]

I'm first on a list for a 125 and at 220lbs I'm soaking up the information on BBKs.

Is there a definitely 142cc kit now that webike has more options?

 

[m in sc]

ive been running the 143 for quite a while as a few have.

heck you can go to a 170, 181 etc 4v if you're feeling frisky with a standalone ecm.

 

[SLO]

I'm first on a list for a 125 and at 220lbs I'm soaking up the information on BBKs.

Is there a definitely 142cc kit now that webike has more options?

YUMINASHI DIRECT SAlES 143cc kit with 238 cam was around $ 256:00 dollars delivered. Not using a fuel controller,as per YUMINASHI,you do have to upgrade to a 150 injector,as well as open intake and change exhaust.Check gap on rings before install,if anything it is the coating on rings from manufacturing that might have to be removed. I have a motorcycle now! Actually performs GREAT! If you want to go 55 mph for any length of time,get another bike. Fun as can be on back roads and twisty's in mountains.

 

[Konik]

Does anyone on the forum have a 181 kit installed and can share any experience with it so far? I'm trying to find out as many things about it as possible before I pull the trigger. I want to keep my reliability but also increase my speed/hill climbs by a bit so atleast im not holding up traffic/being able to keep up on 55mph roads. I do not have an interest in going on a highway as i prefer to take roads/trails less traveled but just end up on 55+ mph roads in between.

I read a bunch of positives/negatives on FB land groups depending on who's selling /buying but curious if anyone on here has it.

Also, I signed up for SCBR next year, the kit would help with some sections for sure as 400+ sections on road with low speed would be extra slow.

Thanks

 

[Shoot870p]

What is the SCBR event, for those of us in the dark?

 

[Konik]

Scooter Cannonball

8 Day trip across the US with an average of ~400 miles per day

https://scootercannonball.com

 

[Shoot870p]

Good deal!

 

[SLO]

Good deal!

BANG! Someone say shoot? I would not ride with anyone who thinks that would be fun. What happens when they run out? METH or COCAINE ? Go SLO and enjoy the ride!