TF100 issues

[Bert]

Having made a start to my return to bucket racing over the weekend at manfeild, i ran into a couple of issues (as normal). One I am seeking some advice on from you lot.

I'm having issues with a slipping clutch, it revs nicely into band (quite a high reving monster being short stroked and over square) and then starts slipping. once it get really hot it seems to go away (well sort of) though i was pissing around with the cable adjusters during the rides as well.

I've put a new basket (well second-hand but near new) when i rebuilt the motor before taupo; and newish plates and fibres etc. but this seems to have made no real difference, (it was happening before hand, but it was the less of my issues at that time). the basket i took out had about 10 degree movement (read: slop on drive gear) were as the newer one felt a lot firmer (I'm assuming they have some form of spring loading??)

I'm running good oil (name I can't remember).

looking into it more I was wandering if the clutch springs are to soft ? or do i need to look into different plates?? I also had a though about oil density maybe to heavy?? the cable seems to be moving well enough as well.
I haven't really been able to find much about these clutches other than the vintage MX (but they are slightly different.

So any ideas, insight, knowledge or experiences that could be imparted on this issue?

(and no I'm not getting a four stroke)
(the other issue is that i just need to man up!!! aye Rich)

[speedpro]

You can screw the springs in a bit more. Do them one at a time and make sure you don't screw them in so far that they stick out the back of the clutch and snag on things. A good idea is to make or buy a hook to pull the springs out when you are putting the little pins back in. I only ever had a 125 bottom end and didn't have problems with a 19.9hp engine so I wonder if the 125 has an extra pair of plates. Could be worth checking out.

[F5 Dave]

Mike is right, just wind them in. A spring puller can be made from a spoke & 3" sawn from the end of the broom. Drill a hole & thread the needle through with the nipple. Sharpen the spoke end so it is a hook to pull with, but they are titchy little buggers so you will need some pliers to unhook & some safety glasses & some rude words.

The freeplay is common but not nice. Can be ground/drilled apart & some spacer, nylon or whatever to pack the rubber shock absorbers in back of clutch drive. then has to be riveted back together. On the 50 I used ht bolts & threaded the basket. Not sure how keen on a bigger bike.

[Bert]

Great, thanks Mike and Dave; had a funny feeling that one of you would have some solutions on this one.

I think I am running a 125 bottom end (internals), but the donner clutch might not be; so I will be checking that firstly.

as for the springs, cheers I didn't know that they could be wound in for more tension; so that's a great starting point as well.
when attempting this should one check for linear loading weight (tension) across all springs, I assume that if they aren't equal things might misbehave ???

and as for the spring pins; yes safety glasses are the go. Along with a clean work area to find them again...

Thanks Guys

[ajturbo]

or just use.."clutch saver" oil
Spectro i think

[Bert]

Hi all.

well the clutch suggestions nearly worked, only slipped a little bit. so one down, Thank you all for the input.

So here another one.

After a goodish weekend in Wellington, I started to pull down my engine to replace the broken casing (engine mount broke with some casing as well) which requires a near complete strip down.

anyway, attached are a couple of photos of the piston with funny burn marks (matching the exhaust port shape) and the exhaust side. (plus the first ~inch of the exhaust was a "not so nice" grey colour as well).

now it was suggested that maybe I had my exhaust lengths incorrect? and maybe this is so given the piston marks and grey header.

Any thoughts on the cause of the marks? or if it is a major issue or not?

This piston has only done about 2 hours (Taupo GP, Manfield and Wellington); not a pretty sight

[Ivan]

just get a four stroke

[Bren_chch]

What is that single ring piston from?

[quallman1234]

just get a four stroke

Just get a bucket.

[NOID]

iv got a rope,

well tie ur engine to the end of it then

ill have an anchor for my dinny

man you pull that engine to bits alot, get a four stroke iv poked mine with stick once

unproductive i know

[Bert]

What is that single ring piston from?

KT100, with a shorter stroke longer rod. I would not suggest this mod to anyone. though the pistons are cheap the rest is well lets say not.

just get a four stroke

now where's the fun in that.

iv got a rope, well tie ur engine to the end of it then ill have an anchor for my dinny

man you pull that engine to bits alot, get a four stroke iv poked mine with stick once

unproductive i know

hahaha, its only got to last a few more meetings. then the old girl will be relegated to under the bench.

Anyway, no one yet has provided some insight.

[Ivan]

haha its coming

[speedpro]

My MB runs KT pistons and the stroke has been reduced so I know your pain regarding reducing the stroke.

If I had to guess, I'd say you were getting blowby, typically from a well used piston and saggy old ring. Good thing with KT pistons is you give it a hone to straighten the bore and squeeze in the next size piston. Question: what piston clearance do you run when you first assemble it with a new piston?

Short stroking a piston port engine would have been some fun with the intake versus exhaust port timing

[Bert]

If I had to guess, I'd say you were getting blowby, typically from a well used piston and saggy old ring. Good thing with KT pistons is you give it a hone to straighten the bore and squeeze in the next size piston. Question: what piston clearance do you run when you first assemble it with a new piston?

Short stroking a piston port engine would have been some fun with the intake versus exhaust port timing

Hi SpeedPro.

Well; with this piston, I had the kart shop do the hone and piston/ring fitting, so not sure what the final clearance ended up being (I know it had to go out to the next size piston to actually get the bore shape right). but i wouldn't have though they would stuff it up to much (given the length of time I've known them)... but given the slop that is now there, I think you might be right;
I just found it interesting that i had a near perfect image of my exhaust port on the piston face, and did wander if something might be up with the exhaust lengths.

port timing, ummm yip, lets say I've made a few errors with this and learnt a lot regarding what doesn't work...
Biggest lesson was that I should have had it re-sleeved at the start and carried on running the RG400 pistons rather than heading down this route (and years of frustration).

[bucketracer]

as for the springs, cheers I didn't know that they could be wound in for more tension; so that's a great starting point as well.
when attempting this should one check for linear loading weight (tension) across all springs, I assume that if they aren't equal things might misbehave ???

I know that Dad does a quick check of valve springs by sitting one on top of another, then squeezing them up in a vice, a week spring will noticeably collapse more than the other, I expect clutch springs could be checked this way too.