Jump to content

Tl 125 Bore Or Stroke


dgraf
 Share

Recommended Posts

kinda miffed on which way to go, Are the liners any stronger for the big bore kit,(cyl. is a 122cc) and I know there is a 124cc, but can the 122 cc cyl. be used? Or is it better to do the stroker kit. any help would be kewl. All I know is that stock is a little on the soft side(ha ha) and this will be my 5th TL to revive.

Link to comment
Share on other sites

 

122 cyl can be used to bore up to +/- 140 cc (cb550 piston)

124 cyl for up to +/- 150 cc (cb750 piston)

stroking the engine is not evident: if you're not able to do it yourself > expensive.

(maybe look for a 200cc engine will be easyer? (tlr, ...))

Link to comment
Share on other sites

 
 

140 or 150 is not the way to go..................simply reline 64.5mm piston for a 180 kit, 25% power increase, just tune carb to suit, kits bigger than this are lumpy and oilways have to be redirected, (more expense) kits available of the shelf exchange for

Link to comment
Share on other sites

 
 

I've built (WITH A TON OF HELP) a big bore, stroked TL 125.

I'd never do it again. It's way too much trouble. I think I'd

get a 200,and be done with it. The stroked / bored engine

will have problems with the TL kickstart gears.

BTW, I still haven't started it up. I'll let you know how it

works when I do.

Link to comment
Share on other sites

 

stu, do you recommend any head work? also any idea how long it can be run before it needs to be re-ringed(without grenading the top end) I read somewhere a national rider blew the piston at around 20hrs with the 180 kit.

on a lighter note the swingarm came back from the powder coaters(bright kx green) frame going in next should have pics soon....

also thanks for the all the replies out there guys!

Link to comment
Share on other sites

 

I have a TL125 with a 168cc big bore, shortened 200cc cylinder, bored cases, some head work I am told. I bought the bike this way in 2003 (?) and it still runs as strong today as when I first got it, better actually since I have the carb problem straightend out. Points, plug, oil changes and clutch are the only things I've done to it.

Stu I am interested in the 180kit as I am currently building another bike. Please send me more info.

Thanks, Scott

Link to comment
Share on other sites

 
  • 1 month later...
140 or 150 is not the way to go..................simply reline 64.5mm piston for a 180 kit, 25% power increase, just tune carb to suit, kits bigger than this are lumpy and oilways have to be redirected, (more expense) kits available of the shelf exchange for
Edited by tlrs
Link to comment
Share on other sites

 
Guest majestyman340
I have a TL125 with a 168cc big bore, shortened 200cc cylinder, bored cases, some head work I am told. I bought the bike this way in 2003 (?) and it still runs as strong today as when I first got it, better actually since I have the carb problem straightend out. Points, plug, oil changes and clutch are the only things I've done to it.

Stu I am interested in the 180kit as I am currently building another bike. Please send me more info.

Thanks, Scott

Was told many years ago by someone that worked for Honda UK, and was deeply involved in the works trials effort, that the main problem with bigger bore TL motors in trials applications is the very sparse finning, which means the motors run very hot when they are used for trials, and that this can cause problems. Not sure if this is right or not as I have seen plenty of 150cc TLs that seem to run just fine, but do remember the finning on the TLR250 I had was very different to the smaller cc bikes.

Link to comment
Share on other sites

 
 
  • 2 weeks later...

majestyman360,

I have to agree that the small fins are a problem,however, the 200cc cylinder has much larger fins than the stock jug albeit not as large as the fins on a TLR250 jug. The larger fin size is not initially noticeable to the casual observer so you maintain a stock apperance. I ride in the mid-Atlantic region of the US near Washington D.C. and it can be quite hot and humid (90+ F, 90+ humidity) here in the summer. The bike runs ok in the summer, sometimes I need to ride around a field or parking area for five or ten minutes to cool the engine down. Currently temps are ideal at 45-55 F, the engine loves these temps!

swooshdave,

The heatshield on the carb is important as well. I have made replica heatshields from a fire retardant phenolic to preserve my original. It has been on the bike for several years now.

A few years ago I was at an Ahrma Trial at Mid-Ohio, hot and humid. Ran into a guy with a stock TL who was having problems, his heat shield was broken. My bike was running fine, he asked about the heat shield, told him it was necessary, next loop saw him again with an improvised aluminum foil shield. His bike was running much better.

I like your heat tape wrapon the exhaust, I'm sure it helps also. I have thought about ceramic coating my exhaust. Any thoughts? Yes, I know it's expensive...

Link to comment
Share on other sites

 

The exhaust bandage is much more expedient. You might also look at tweaking the exhaust routing to move it farther away from the carb.

I think many air-cooled trials bikes probably are overcooled, as they run for 3-5 minutes and then are shut off for 10-15. But you can certainly get into a "heat soak" situation if you get out of that mode, especially in hot weather.

Coating the exhaust port will help to reduce the amount of heat that stays in the top end. Coating the piston crown and combustion chamber will also help.

What might be a good move on a TL125 would be to see if you can fit the oilpump from a 185/200. We tried to get a small roadrace Formula class going that was based on the CB/CL/SL100/125 engine and I think that with the engine I started on I did fit a 185 oil pump. Circulating more oil can help to get the heat spread around where it can be radiated away. But the little Hondas do seem to want to run hot. My 175 based roadracer would get the cases much too hot to want to touch. A synthetic oil that would take more heat might be a good plan for a TL.

You can always weld on fin extensions. A friend has done that to quite a few XL/XR350/500 Honda singles.

cheers,

Michael

Link to comment
Share on other sites

 
  • 1 month later...

Well, I said I'd let ya'll know when it was running. It is!

Feels like 3 times the power of the 125. Smoking like crazy though.

I'll have to see if a valve seal popped off or something.

I may have to decrease compression even more. Way too jerky

off the bottom. I'll play with the ignition timing and the valve timing first

though.

Link to comment
Share on other sites

 

The picture I posted above was a friend's TL125 with a Powroll kit. Don't know which one, I assume the 145cc.

Ceramic coating of the exhaust is an option, although the exhaust wrap was a wee bit less expensive. There is also (I believe) a Sammy Miller Exhaust, although it may just be the muffler and wouldn't do much for the pipe location (not that you want to move it too far out as it is).

Link to comment
Share on other sites

 

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
 Share

×
  • Create New...