Ok so here we are as promised in teh 'Introduce yourself' section..

I had the XJ598 running up the road in the last couple weeks for the first time following a basket-case rebuild and was pretty chuffed. but now it simply will not start. I rebuilt the top end with new rings set valve shims etc.. before instaling the motor so I'm reasonably comfortable with those mechanics. I also have the correct TCI for the Radian pick-ups and I'm getting a spark. When  I initially tried the motor with XJ600 (BS32) carbs  it wouldn't start for love, money or Bradex easy start. I then fitted the 550s BS28s though and all went well - for a while and as said I even manged some forward motion... I have since also tried starting  it from my auxliary tank but zippo. Ideally I need some FZ600/Radian BS30 carbs, but I'm struggling to see why it now won't start on the BS28s (which have been well cleaned BTW). It does start on a few breaths of Bradex so I'm sure it's a fuelling issues. I will likely pull the carbs again to check levels,jets etc.. again but if anyone has another suggestion I'll gladly hear it... Cheers J

Have you tried it with the tank fuel filler open? Sometimes it can be blocked especially as it's been sitting around for a while. Otherwise have you got an external fuel bottle to try to start it without the tank attached, you can then see what's happening at the carbs. Just a couple of thoughts on your problem, your right if it starts or fires with Bradex then it has to be fuel related.

Edited November 19, 20159 yr by slice

check for cracks in the inlet manifolds too, it might be letting air in somewhere.

 

do you have  a compressoin checker?

when I did my xj motor, I inadvertantly skipped a tooth on the exhaust, it started but would rev over 5 k. luckily no damage was done.

I would double check timing and everything to get a base line, then have another look at those carbs as mikunis have some real small holes and needs a ultrasonic bath to get rid of detrious.

Thanks for the replies..

Compression tested ok after I had reassembled - only one pot which had suffered water damage was down to about 135.

Anyway went back to it tonight to check float levels ( a bit low but not too bad) then I drained the carbs fully ( and noticed some slight debris) and swapped back to my aux tank. Now it starts (!)  a bit rough mind you but at least I'm back to where I was. Last year I tried some electrolysis on the tank which worked but probably not well enough.  I'll get some brick acid at the weekend and give it a go with that I think..

Cheers

J

J

Would suggest you don't use Brick acid (Hydrochloric acid) to clean your tank, have you tried this? http://www.doityourself.com/stry/5-tips-for-cleaning-motorcycle-fuel-tanks

It takes a bit longer to do but is better than chucking the stuff your thinking of in. Just a suggestion mind it's your bike after all.

Have you tried it with the tank fuel filler open? Sometimes it can be blocked especially as it's been sitting around for a while. Otherwise have you got an external fuel bottle to try to start it without the tank attached, you can then see what's happening at the carbs. Just a couple of thoughts on your problem, your right if it starts or fires with Bradex then it has to be fuel related.

Yes, I did the nuts and bolts in the tank thing before the electrolysis (the bike was in bits  for 14 years before Imade my foolish ebay bid - the power of nostalgia !). In fact I've opted for phosphoric acid which is a widely used rust treatment/converter so we'll see how that goes. The stuff I ordered is 85% concentrated but I read 10% is still Ok for this purpose so I'll be diluting with distilled water I think.

Cheers

J

Oh OK that should work, good luck.

Phosphoric acid and water, that's basically what Jenolite is, also makes a good flux when soldering if you have nothing else.

Ended up usig a 15% concentration of phosphoric acid after cleaning the loose stuff out with a handful of screws and diesel - seemed to work well.