10 replies to this topic

[Galilee]

Hi I have a 1996 TDM 860 4TX and have run into a recent problem.

 

The bike has suddenly started surging when riding at low to moderate speeds and at 2-3k rpm. it also surges at moderate acceleration, but runs smoothly at hard acceleration, high speed and at high rpm.

 

The bike has a Delkevic exhaust (2-1 short muffler) and hasn't been re-jetted, but has worked very well with the same setup for 3 years before this.

 

 

Any ideas? i thought it was the 900 that had this problem.

[dapleb]

What miles (or them other funny things) are ya on now Gal?

Initial thought would be HT leads or coil. Is this in wet conditions?

[Galilee]

it is at around 100k km or 62k in them other funny things.

 

I had the HT leads problem in wet conditions and did the mod with amalgaming tape on the leads which seem to fix the wet running problem.

 

The surging doesn't feel as abrupt cut in power as it does when a cylinder (or two) cuts out.

 

Update: after running it hard for a few minutes (ok, more than a few minutes) the problem seems to be gone.

 

Was it particles in the carb jets or something like that?

[Studley Ramrod]

It might be a worn/holed/stretched fuel pump diaphragm.  Low rev vacuum and it struggles, high rev vacuum and it delivers fuel better.

[Galilee]

Time to try the electric fuel pump mod maybe?

[Studley Ramrod]

Or a new vacuum pump.  The one you have is over 20yrs old so a new one should last just as long really.  You could also try a cheap chinese copy one.  Prolly best to wait and see if the problem crops up again first though.

 

You could check the fuel filter and float bowls for any crud.

[dapleb]

You can make a new diafragle thing oot of arsey Tate's even as a temporary measure this will help diagnose if it's the problem.

[dandywarhol]

If it's been laid up for a while then the ethanol in fuel could have perished rubbery bits. Great Viton kits available from https://www.litetek.co/contact.html

[thunderdrum]

had something similar on my 99 4tx after sitting for awhile over Christmas put silcoline pro fst in fuel this now is running smoother as think jets may have been a bit gummed up

[Apache]

Lots of things already suggested but I had a nightmare low speed lurch/misfire (mostly when filtering) but it ran fine once past the low revs...Tried everything thinking it was ignition at fault. I was due for a tour and thought *u*k it, I'll risk it. It got me to Spain and back and threw a dickie fit 50 miles from home but made it back. Finally tracked it down to torn diaphragm in both carbs. They were absolutely shredded. Mileage was at 70000 at the time. Used nrp diaphragms and still good at 112000..hth.
It is fiddly possible to lift the carb tops off to inspect but be very very careful not to drop anything or lose the mini O ring in the lid....

[MickC]

Mine does the same in that it seems to loose a cylinder or cut out for a second at slow speed I too would say in the 2/3000rpm mark but sometimes higher.

I have a second 4tx which did the same so thought it was normal at the time both bikes had carbon HT leads and taped up-- different coils same carbs (carbs have been cleaned a few times and diaphrams seem ok) but my main 4tx has used a different set of carbs and still did it---same Delkevic 2 into 1 and I have now replaced the diaphram pump I have also put seafoam in the tank a few times--It still does it but on some rides it does run cleanly so I recon its fixing itself :good:So I will leave it for now and see what happens.