fuzzblaster

Hi all,

Bike particulars: RE Thunderbird CDI engine (kick start only) 2004 model
Kms: 55,000
Location: Mumbai

Here's the problem

I start the bike using the decompression lever, no problem
I start the bike without using it, either the bike gives a major back-kick and dies/ or the bike runs perfectly for abt 500mtrs n thn dies

at both the instances, the bike just abruptly goes dead. no sputter nothing.
no amount of kicks get the bike started thn. the bike is as good as dead.

here's the weird part. I leave the bike alone for about 15minutes and start, it starts like a piece of cake in one kick without any signs of any problem

Troubleshooting done till now:
01. tuning perfect, carb checked
02. electricals ok (tried starting with bypassing the ignition switch, didnt work too)
03. spark plug ok
04. CDI running fine
05. always turning the fuel off whn i dont ride
06. engine kill switch tested n working

mechanic says thrs no connection with the decompressing bit. says tappet adjustment will solve it. i doubt it. if it was tappets, bike wouldnt have started in d first place at all, isnt it? and i chkd the tappets. the pushrods rotate properly by push of thumb. aint tight.
even if they r losr, thy wuldnt get the bike to stall isnt it?
will get tht calibrated anyways

I have a feeling thr maybe sum residue of unburnt fuel inside the chamber or so, which refuses the let engine start. maybe thts y the shut time of d engine of 15-20 mins must be letting tht choke-up subside after the stalling.

i say this because a lot of times, during decompression after the bike has stalled, the bike gives out a loud mis-firing sound and then kick starting works like breeze.

any sort of help will be greatly appreciated. thanks a ton in advance!

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Noor

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johnnyworks

hi fuzz.
I don't think its the tappets but anyways, chk the tappets and push rods as they cud be getting stuck when they are heated up to operating temp. Check their play when the bike stalls or when the engine is heated. Also, i would suggest to open the rocker covers and reset the tappet push rods and tappets making sure they run properly. there's nothing like a visual check when you are trying to isolate a problem. ground rule, leave nothing to chance.

There are 3 other things that come to my mind w.r.t your issue.

1. To me it looks like your bike is running excessively rich. If you are running a ucal mikuni BS26 carb, just check your slide and make sure it slides back when pushed up. Slides in these carbs do get stuck from time to time bcos of fine grime or dirt that settled on the slide walls thus obstructing their movement back. So basically when you open, the vacuum pushes the slide up but the grime holds it up there, so much so, that when you close, the butterfly valve shuts but the slide still remains up thus stalling the bike immediately. Eventually the slide would come down slowly back to the default position and thats when the bike starts again. you cud use the finest of emree or polish paper to just smoothen the slide and its walls and while you are at it check the rubber diaphragm as well. if i looks cracked or sticky then replace it.

The other is your plug. in any case i would suggest you just get a new plug and check it out. Some plugs work when they are cold and short when they get warm. they dont sprk well hence causing backfire.

One last check is to make sure fuel is flowing fast enough from the tap into the carb. Remove the float bowl and check the float and the pin and make sure the flow is fine. Cos if its not then the bike would die of fuel starvation and wud restart when the float bowl is full again.

These are all compiled from my personal experiences on my own 2 bikes. Some of these things have happened to me, and mech have looked for the bigger issues, i have figured some of them out myself in the city and on long rides. It takes patience and know how to get around it.

Update us. cheers.

fuzzblaster

hey, thanks a ton johnny,

will get a check done on all of these asap. very high chances of you being right, whr we keep looking for larger faults and the real problems lies in these smaller tweaks which can easily get bypassed.

shall keep you posted!

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djvenom9111

Isn't the fuel cap clogged? It could be one of the reasons too.

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fuzzblaster

will get that checked too. tomorrow is the day for getting all of these things out of the way. wil post here on the progress.

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fuzzblaster

Case Solved:
CDI used to stop functioning abruptly due to overheating and resumed after cooling down. replaced it and the machine runs like a cake now. got visibly better power too.

Thanks a ton Johnny and Djvenom for ur inputs. im bak on d highway

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johnnyworks

kudos to the troubleshooting.Tricky, cos u had mentioned u had checked that.....! happy riding..!