500 Two-Stroke Tech

David, Are you running stock motor carbs airbox pipes? It sounds like your saying if you ride going up and down the revs, shifting gears it runs good but if you hold a steady speed for a long distance it goes bad. If so I would ride till its going bad, kill the motor coast to a stop and check all p...

So finally had time to go for another test run. Problem showed up as usual after accelerating up to 85mph , holding 75 mph and riding for 1 mile. Stopped and took off fuel cap and all good for a few miles but then it started again ( so definitely not tank air lock ). when i stopped it was the top le...

Sorry you are having such a time of it can be very frustrating but in the end it's just an engine so there will be a solution. From what you wrote about the the last stages it did run properly until it ran out of fuel. Sounds as if something has been sucked into the carbs and you have had the feeds ...

Thanks again. Mine is an rzv jap import (derestricted) with the original cap as far as I know. Definitely no third pipe underneath like the lh tank would have. Can these filler caps be stripped down ? Is there a pin hole that gets blocked? Will certainly do the run with cap removed /taped aperture a...

Thanks for the replies www and mk.

Tank venting also suggested by dealer I bought from. Can't find anything in service manual. Does tank vent through filler cap? Anyone had problems or experience of solving issues with this ?

Thanks for all your input Siverstrom really appreciated. Couple of quick checks this morning. Gearbox oil is full. there is a slight oil smudge next to the pointer on the outside of the fuel cap which I haven't seen before. Must check out tank breathing as suggested. Back in a week but will be on li...

Many thanks silverstrom. will get to work stripping the carbs. What i dont get is that if there was an airleak or failed seals wouldn't this be a permanent ongoing problem once warmed up so that when the engine is really sucking at max acceleration in second or third gear wouldnt I notice a signific...

Struggling to understand the behaviour of my bike. It starts up fine, idles and pulls sweetly and then powerfully as the revs rise over the first few miles. Then i go on a dual carriageway and it blasts up to 80 mph but when I try and maintain this speed after a minute or less the engine seems to lo...

Hi I have recently bought an RZV500 and had engine the derestricted fromJap spec. plus a general going over with new crank seals power valve set up etc. What I don't understand is the received wisdom that the bike is a bit of a sheep in wolves clothing not especially fast or exciting like the RG500....

Hi Marty the seals and dust covers are available from the yambits site. I didn't replace the bushings only 8k on mine. I used the 18mm box spanner from a very old set in my own tool kit. Full sets including both the ones you need are on ebay for a fiver - very versatile tools. You can take off the t...

Mystery solved re the tap. Dealer who supplied it opened it to find clover leaf seal missing. obviously nicked then tap returned for refund by some amoral previous purchaser ! Taps may be a bit unreliable but can't really be expected to work without a seal

Thanks Colin. On seeing your post I rushed to the garage full of hope that I might be able to do the same and get my tap working but sadly no luck so it has to go back. Your pipe routing is the same as mine and your second photo shows the pipe close to the corner of the cylinder head but can't see i...

Thanks Paul The New fuel tap is definitely faulty , fuel gushes continually from the pipe when disconnected from a carb in normal position. Wonder if some naughty person has previously ordered it, swapped over seals and returned for a refund of £120. Anyway it,s going back and I don,t want to open i...

Have just done this job and found the info on here really useful so here is my contribution for anyone searching on this topic in future. I had a manual in English for an RD500 and it was the air suspension on the RZV that caused me grief both removing and replacing the forks. To remove the forks yo...

Hi Have got hold of a lovely RZV import which has been standing around for most of the last few years. Carbs were overflowing and in trying to rectify this noticed fuel dripping from carb feed pipe with carbs off although tap was on normal ie should have been closed with no vacuum. Cleaned out and r...