48 replies to this topic

[dandywarhol]

https://www.sportrid...up-guide#page-7

 

Possibly a bit OTT for your purposes but you can pick the bones out of it

[RobinHood]

Well the problem reappeared and became far worse while attempting to go on holiday. Took it to a garage in Devon with the AA and they found water in the shroud by the left plug. Dried it and resealed it and couldn't get it to misfire again but when I rode it away it was just the same as before. Have been told I need a new coil to begin eliminating the problem. So I'm in the Devon area not sure what to do at all. Is there anyone in Devon who might be able to help me diagnose it at least? Its a nasty misfire basically. And I depend on the bike so don't have the chance to take it apart and risk not getting it sorted in good time myself. Any good suggestions appreciated

[dandywarhol]

Have you changed the HT leads as suggested. The Yamaha ones are steel cored and corrode at the ends. You need 7mm copper core leads from an old school auto accessory shop - they simply screw onto the colis and HT caps

Edited by dandywarhol, 12 April 2018 - 10:09 pm.

[RobinHood]

No dandywarhol I've not. I just don't have the know how to be sure I'd get it done successfully in the little time I can spare before i next need it. And the mechanics i've had look at it tell me its not necessary. It is on my list for sure but in the meantime I have to short term problem solve

[itchyfeet2]

The problem does sound electrical. I wonder if the bike ran properly in the mechanics place as it was warm and dry? There could well be moisture somewhere. Changing the HT leads is quite straight forward, if you can get it to a machanic and have the cash just tell them to do what has been suggested and check the connections and earth to the coils.

If you cant get to a mech and are desperate to move the bike you could try spraying the HT leads and all plug connections with a good moisture inhibitor like AFC50 (from a bike shop) and see if that helps in the short term. The AFC50 will force out any water from the connections and may well help. get the tank off and try drying everything with a hairdryer first.

[RobinHood]

Thanks itchyfeet i think my plan is to get it to a mechs and get an overhaul of the firing system as I can't afford the time for trial and error. New coils and leads on both I'm thinking. I'm not having any luck sourcing ht leads anyone know where i can find them? The moisture they found has been dried out, and the water bleed hole is clear with nothing coming out. The problem has been getting much worse in ideal weather conditions so i don't think it is rain related at least...

[Apache]

Not a niner but I pulled a 4tx out from winter storage last month to find it had a tickover / low speed misfire on the right cylinder. Fine at higher revs. I was convinced it was a blocked pilot jet so carbs out and checked. Perfect. Reassembled,all ok. 2 days later misfire returned. Swapped plugs and caps from another 4tx. Still the same. I had a spare coil so went to replace it to eliminate as the cause. I couldn't pull the spades from the coil by hand. Pliers did it and the build up of crud between the coil male pins and the harness terminals had welded the terminals in place. So,flat blade screwdriver to scrape the coils back to bare metal ,some 600 grit paper up inside the harness terminals, Vaseline everything and reassemble.Did t'other coil while in there. Been perfect ever since, 1000 or so miles. Definitely the cause. I'm presuming it was ok at higher rpm because the voltage rises and overcame the crud resistance.....Anyway, might not be your problem but worth a look..hth.

[RobinHood]

Very interesting Apache. I wish I had the time to fiddle and problem solve. I've just bitten the bullet and ordered new coils from fowlers. Of course its very likely that the coils in place are like you describe, but being time starved replace vs repair is the obvious route. Unfortunately as I don't want to rely on replacement when the original should be able to be put back to proper use.

[RobinHood]

I ought to update here that since the coils and leads were replaced, she's been running like she's supposed to. Ran perfect for the last 300 miles and reminds me why I don't think I would ever sell my tdm