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[Bullet Train]

A rare posting from yours truly, but I'm gettitng desperate? My 2000 model 500 just will not run properly with the choke off. After the winter degreasing chore on 10th March,  a full service was done. It was running fine but since then I've spent many hours trying to fix this but, even after a second full carb strip, clean and blow dry it still wont run right. Bog standard VM28, air filter and exhaust, points, ect. I think I've checked or changed every part of the Ignition/Carb system 3 times over but still cant work it out. It starts, runs and sounds spot on ,albeit way too rich, on full choke. Shut the choke and it'll die very quickly. I've had well over two years and 8000 km's of all year riding, done a lot of all the usual "tinkering"  to keep it sweet and I've only been stranded once, by a puncture in February just gone actually! Fixed that myself with a new tube, no problem, but this issue has defeated me. I dont have a spare carb to check if I've missed something and dont really want to go down the Amal/Freeflow Exhaust road? Any ideas welcome, before winter returns?


Bullet Train

[Norm]

 Don't overlook the spark plug. I had a breakdown last week and was totally convinced it was fuel, it coughed, spluttered, backfired and carried on till it stopped. Tickle it up, first kick fire up, go 50 metres and the performance would be repeated. This continued for some ks it would run fine untill I tried to open the throttle and the performance would return. Pulled the float bowl off, looking for something in there, nothing, changed the plug, (had spark and looked clean) and all problems went away I had this problem last year on a trip to Tassie and I could only get 150/160ks from a plug and since returning to the mainland I have not had a spark plug problem and I have done about 6,000ks on that plug. Just a thought

[Alan R]

Hello matey ------ where abouts are you ?? I have a complete VM28 spare at the moment PLUS a bike that's running 100%. I could lend you the carb to try-out. That way you can pin-point / elimenate certain areas. I'm in Shroshire. 

[Riggers]

Hi Bullet Train - Just a thought mate but is the pilot jet clear?


Cheers.

[John J]

Hi, Have you made sure that the choke assembly is air tight. The O ring on the plunger may be leaking or the rubber cover on top of the plunger. I put just a smear of sealent under this just to make sure.

[ChrisD]

Hi Bullet Train


I had a similar problem on a matchless a while back after a long winter. The long delay with petrol in carb had plugged the pilot jet airway. as Riggers suggests.  Poked with bristle and much carb cleaner and all OK. Cheers, ChrisD

[Chris]

How about water in the fuel?


Are the points and spark good?  In 40,000 miles I have only had problems with air getting into the intake and water in the carb/fuel.  The other snags regarding running are all points/condensor/plug.

[fjr]

You mentioned that you degreased and washed your bike, could it be that your air filter element has got wet and is causing this problem ? I had a similar prob with my bullet and i used a power washer.

[Bullet Train]

I've had another go this afternoon, but still no joy. Check these "sounds" out on Youtube. I've put a lot of detail in the descriptions. Something here is staring me right in the face on this one?


http://youtu.be/uKmlRcTA6Xw

[Riggers]

Hi Bullet. I've watched the video. I don't have a ready answer I'm afraid, but logically thinking this is what I reckon. What you're doing when you put the choke on (on a Mikcarb) is boosting the fuel supply.  When you turn the choke off you are reducing the fuel supply. Therefore your problem is lack of fuel. For whatever reason without the choke the carb is not delivering fuel to the engine. The pilot jet, and needle jet do not seem to be delivering fuel.


Of course I may be wrong but that's what logic seems to suggest - to me at least.


Sorry I can't be of more help.