Disappearing clutch

[Eljefe]

Guys
Long story short, 750 resto gone wrong 5 years ago the old doc ground to a halt, fuel starvation, so decided to do a full resto on the 49000 km bike. 4 years later got round to it and put an as new 750 back on the road, initial fuel starvation cured with carb overhaul kit, clutch stripped and checked engine serviced fork oil, tyres, chain set etc etc. 150 kms later a lot of oil had disappered along with clutch adjustment. no oil leaks, no smoke. Topped up oil adjusted clutch off we go perfect 150 kmsish later same thing and so it goes on. Clutch stripped, checked, Fine 150kms same again, fit new clutch change oil. Whats going on when its working it works perfectly, when its not the clutch drags and disappears after 100kms or so. Prior to the refurb gearbox and clutch worked fine. The bike has only done 49000kms. We are just outside that little village of Witzend right now, has any body had any thing like this happen before, I am reluctant to pull the engine down!

CHEERS

[DHC6]

If the clutch does not get enough oil it starts to drag and/or slip. A clutch cannot cause oil consumption.

Q1. Did you take the cylinder off? If so did you hone? If so did you install new piston rings?

Q2. Ask some one to ride behind you and ask if there is an oil smell, often caused by old dried out valve seals/worn valve guides. At idle there is not a lot of suction but at higher rpm there is. An engine that was standing still for some years has dried out seals, probably the RH side crank seal as well.

If the oil level goes down the oil temp goes up and causes more oil consumption.

Good luck

[Eljefe]

DHC6
Thanks for replying on the mystery.

Correct the clutch can't use oil and if short of oil will slip or drag.
All we did to the engine was refurb the carbs, we took off the clutch cover split the clutch pack and reassembled, as all the components where fine, we also fitted a new clutch cable.
There is no evidence of burning oil, leaks, all the usual checks have been carried out thoroughly.
the last time it faulted we dropped it in at the local KTM agent who checked it out and fitted a complete new clutch assembly.
No change!! I can't understand how you can have a perfectly adjusted, functioning clutch that disappears with 100kms
Its looking like we will have to pull the whole engine apart and check the gearbox out completely.
I do think that the fact its been stood all that time is the oil loss problem and it is separate from the clutch problem, but has it caused the clutch issue??

You would expect this must have happened to someone else over the years

Anyone else??

[BigBob]

Clutches on Bigs never give problems with normal usage, so this is very unusual
I would check out the clutch rack and pinion first to check if teeth/splines are missing/worn.

[Eljefe]

OK Bob now I'm getting juiced up, Exactly Dr Big and clutch problems don't appear in the same sentence very often! So are we are talking the splines on the out side of the case that the cable arm works on, i have had to move that for course adjustment during this problem, but didn't notice any damage to the splines. however i haven't looked at the internal mechanism in any detail.
The other inconvenience is that its in Spain at the moment and i was going to trailer it home, but if i can sort it out there that's a game changer.
Thanks for that i"ll look at that first as a likely cause, it sounds to easy but its often those simple things you miss! when you replace the basket plates springs and most every thing else you start to wonder what can it be, i will report back.

Thanks Bob

[BigBob]

[DHC6]

Happened to me (and OR), oil consumption due to valve seals, the higher the temp the more oil is used. It can be very hot in the middle of France which caused a consumption of 1.5 ltr /100 km. In winter none. New seals plus guides/valves solved it, did not have clutch pbms because have carbon plates which can run nearly dry.

I would take the engine out, redo the seals/guides and at the same time put a new cam chain spring in, leave the piston in the cylinder which saves you piston rings.

These engines are really bullet proof with the correct precautions.

Cheers

R

[Eljefe]

Thanks a lot Guys, i"m still pretty sure that the clutch and oil use problem are two separate issues.
So Ive booked a flight out to Spain with the parts i have ordered form CMS to see if i can solve the clutch issue.
I will report back after i have been back to the bike in Almeria"s sweaty summer heat

Cheers
Eljefe

[BigBob]

Where near Almeria?