Bike not runing well

[wurlyvalve]

Hello all,

To start with, my bike has never liked rain. Always had a slight misfire in the rain.

Yesterday morning I fitted heated grips to the bike. whist I was at it I checked the voltage at the coils (after reading plenty about Cobba fitting relays - I used a relay for the grips). Anyway, 0.4ohm drop across the feed lines to the coils and 0.1V drop with the headlights on. ie, 12.3V across battery and 12.2V across ground term and coil +ve pin. With engine idling 14.0V across battery and 13.9V across the coil to gnd pin. I felt it not really needed to trouble my soldering iron just yet.
Riding to the shops and back, 4miles from home, at 80mph in the outside lane in the passing down rain both cylinders cut - zero torque and random backfires coming out of the left zorst. For the next 4hours whilst I waited for the RAC to get me home, the bike did approximately the same thing when asked to crank - backfire out of left exhaust and not start. Two RAC chaps swore blind the electrics were fine and bone dry. Well, they were dry, I could see that too.

Next morning, crank the engine and the bike fires straight up! Grr. But..... she ain't right. Sounds wrong, smells wrong, backfires too much/flames out of exhaust. Sorry, not very scientific. She only runs for about 10seconds and then turns herself off. Like the kill switch is hit. Even if I leave the throttle jacked to run her at 4000rpm.
The battery has taken a pounding. The regulator appears now to have given up the ghost. At idle 11.8V at 4000rpm 13.0V, battery was 12.2V rested no ign voltage. With a jump pack on the battery and a "healthy" 12.6V she still exhibits the same bad running behaviour. So, yes, I'll check the charging circuit but something else is fishy.
The exhaust temps surprise me a little. Both are hot. But mental hot for idle. My 400/600's run about 220c on the manifold at the flange at idle. My IR gun goes FSD (320c)any closer than the bellypan after 10seconds or so at 900rpm.
Could something have gone screwy lewy to make the timing mega retarded? CDI failure? Ignition pick-up drift?

Cheers,
Glen.

[Mincehead]

The moisture issue could well de a defective coil, micro-cracks can open as the coils hard ABS gets warm, moisture then gets in.
The `other` issues may be due to poor carburettor performance, and / or burnt exhaust valves or seats.
Replace the coils or swap out with another TRX owner and that SHOULD cure the damp ingress issues, then set about checking the carb settings as accurately as you can. IF the bike then runs ok, check those exhaust temperatures and expect a motor strip looming if they`re as high as before.

[wurlyvalve]

Yeah, ok. These are my third set of coils in as many years. It's not failed the same as the last ones as there would be one stone cold exhaust pipe - that was a brilliant tell tale.

Carbs seem pretty good. It was running well up until it cut out. I rebuilt with keyster set last summer.

Exhaust valves also crossed my mind. I might throw my comp tester on to her Friday. That would not be a desirable conclusion..... wife will go mental - she's bored of me rebuilding engines now.

Cheers,
Glen.

[wurlyvalve]

A couple years back, someone on this forum suggested my issue might be a leaking fuel cap allowing rain water in to the tank. I'm now really seriously considering this to be the main problem. The bike runs like poo only after hitting the brakes hard (in the rain). ie, the slip road coming off the dual carriage way. Filling up with fuel eases the problem. Riding with a tank bag eases the problem. And leaving the tank off the bike petrol dribbles out of the cap if the tank is full.

Anyway, a pair of DC3-1's are in the post, as are some tinned copper HT leads etc etc.

Cheers,
Glen.

[dandywarhol]

Valve issues tend to be on the intakes - exhausts tend to be ok.

I recently fitted new copper core leads to my coils and caps. The leads simply unscrew from the coils. The Japanese use steel as plug lead core which was corroded and showing a high resistance in my case - new copper core leads sorted out all the wet running issues. Fitting 3 sets of coils may be a way of testing but all 3 sets are probably 20 years old - as are the leads

[wurlyvalve]

Sorry, 3 sets of new coils from M and P (I think it was). Not second hand. The last two sets were burnt out though, the secondary resistances were way off (never both coils at one time, I always had a single to ride home on but I replaced as pairs). Not sure how much I rate new pattern parts. Mind, I do a lot of miles for a biker.
I'll double check the coils Friday but I'm not convinced the coil windings are goosed. The placcy could be cracked though, that is a fair point. And the HT leads could well be shot too. I hadn't noticed any resistance issues across them when I last checked but I'll fit with new, again.

Any roads, new DC3-1's and tinned copper core HT leads are in the post. I'll try them Friday. Also have a MOSFET reggy/reccy in stock that I'll throw on too.

Cheers,
Glen.

[Rod.s]

also check the drain holes in the plug wells

[wurlyvalve]

You what now? Sorry, not spotted them before. As in the cylinder head/cam cover castings have holes for water ingress to drain out from? What a wazock not spotting that earlier....

[cobbadiggabuddyblooo]

On the LHS of the head you will see a small hole...
There is a hole between the 2 plug wells too and it drains cyl 2 into cyl 1 plug well because of the cam chain galley on the RHS

[wurlyvalve]

Plug wells were dry. Holes not blocked. Left hand coil secondary winding had gone o/c. Anyway, cleaned the gasket, seals and chemi sealed the fuel cap back down. New copper HT leads and the DC3-1 coils and she's not missed a beat since - even in the rain. So, rain problem gone.

I'll re-check the exhaust temps another day.

Cheers,
Glen.

[Mincehead]

[wurlyvalve]

Not 100% confirmed yet but.....

The petcock leaks petrol out the vac port. I now get black smoke when cracking the throttle at idle. I've ordered a non-vac R1 petcock to replace it.

I wonder if the hot exhaust manifold was due to excess fuel that at that point I hadn't noticed was from over rich running? I admit that the (I think) right hand cylinder would technically be the super rich one and not both.

I'm still getting 68mpg, the new coils/leads have done this wonders. Will I break 70mpg with a non pucked fetcock? Exciting!!!!!! For an old man like me.

Cheers,
Glen.

[wurlyvalve]

Yes, fixed ex temps. Replaced the petcock and no longer have the clouds of black smoke on first start up. Had to adjust the idle speed a little too.

I used an R1 petcock. With a little fettling to the lever arm and base plate, the lever arm goes to a vertically up position. Bench drilled out the blocked port and now there is a reserve section. I used a pair of individual staggered filter snorkels from an old GSXR400 petcock I had lying around and they just about push into the port holes of the R1 petcock.
Oh, and it appears that it was the left (not right as I first suspected) cylinder that was sucking in the neat petrol from the vac port.

Ex temps are down to 270C about 25mm from the flange. About 240/250C about 100mm from the flange - a consistent distance with the 400/600's. Idle speed 1000rpm+/-50 depending on oil temp. Temps may not be absolute accurate but reasonable relative.

Cheers, fully happy,
Glen.

[wurlyvalve]

Rode in the heavy rain Friday and the bike has turned to poo again. Grrr. Problem was not fixed. Again, left hand cylinder worse.

It's worse after being left over night on the side stand. It's better when I refuel at the petrol station. It's worse on the pilot jet. If I brake and or turn left the problem is there. When I run her after leaving over night she runs on the right hand cylinder only for about 1mile then pulls on both (unless I then brake/turn left).

When the snow/ice came the other week I had to pour some kettle water on the petrol cap to unlock it so that I could fill up. When I subsequently lifted the cap (even though I'd dried off the top of the tank) about a cup full of water that maybe had been sitting between inner and outer part of the cap then poured in to the petrol tank.

My thoughts are still that there is water in the tank. That it's denser than petrol so when left to stand sinks and whilst on the side stand the left hand carb is lower than the right. The carbs are near downdraught (as is the float bowl) and the pilot jet is lower than main jet so braking makes things worse. Maybe there is a drain on the tank that is blocked? Maybe I need to run IPA or Methylated spirits additive.

Lets hope I haven't lunched another coil. This time it will be expensive to replace. And I'm 150miles from home which will be no fun riding on one cylinder.

Cheers, hate this bloody bike,
Glen.

[trixynut]

Looking on the positive side, if its water in the tank its a cheap fix.

Get the tank off and drain it completely, then make sure the breather hoses and any other drain points are all clear round the filler cap.

Best thing for poking through pipes to clear them is an old guitar string or a length of solder wire.

Maybe look at replacing the seal on the filler cap?

If you need a tank schematic, look here....

https://www.cmsnl.com/yamaha-trx850-199 ... ml#results