500 Two-Stroke Tech

"Summer - which year?", no kidding, I'm hoping this year. But it's gonna be close. I'll give it my best shot :grin: @#4: well the "funny" part is that the nut was secured :shock: So it just wasn't tightened properly. Got word from the powder coater, I can pick up the parts tomorr...

Hi all, I have an update on the engine problems. After trying to figure out what was wrong with the engine, after much thinking/doubting, I finally bit the bullet and decided: This is out of my league. I decided to search for some help and the only guy I trust with my engine is Stan Stephens. So I g...

Hi Silverstrom, Thanks again for replying and trying to help. Like I said earlier, it has been quite a journey to get to the point I am now. Maybe it is good to summarize what has been done so far: - it started with poor spark on lower cylinder. Checked were, spark plug (replaced) HT leads (replaced...

Hi silverstrom, Thanks for replying. It has been quit a journey to get to the point I am now. Somewhere along the way the float valves (needles and seats) have been replaced by new, original ones. That didn't cure the problem. But because now nothing seems to "cure" the problem I got to th...

Hi all, Something came up in the weekend so it took another week. I managed to get the intake leak sealed with Yamabond. Checked with pressure test and they are sealed. Didn't have access to the vacuum tester so put the bike back together and tried: :-( :-( . Nope same story: lower pipes remain cold...

Absolutely do not use a compressor

NO NO don't worry, I just meant that I have pressurized air available. The video is at 4 psi.
But thanks for the figures on the vacuum, I didn't have them.

I know what I'll be doing this weekend

Greetz,
Roger

Hi Bengt,

Thanks for your reply. A thin coat of Yamabond it is, no extra gasket.
Uhm, how do you check under vacuum?? I have a compressor so pressure test is not a problem. But I don't have a vacuum pump.
Do I need a vacuum pump or is there a home made setup that can do the trick?

Thanks,
Roger

Hi again, It has been a while since the last post. Didn't do much work on the RD due to some house re-modelling that took a couple of months and it being too cold in the unheated garage to work on it. But with better temperatures I picked up where I left off. Did some thinking in the meantime and de...

You can't even be sure that your new valve sets are ok. Please explain. My philosophy is that when you use new, quality parts, you can assume, no expect that they work correctly. From your remark I take it you assume nothing works correctly until proven?? I'm not trying to be an asshole here, just ...

Why do you want to change the floats without testing them ??? As I mentioned, the floats were pretty crooked when I opened the carbs for the first time. Obviously someone had had a go at them previously. I straightened them out as good as I could and they do look straight, however the one thing tha...

Thanks for the offer Red Baron, but a little ingenuity gets you a long way. Got word from Topham that they don't have the floats listed. They asked for some pictures and measurements to see if any of their stock in the warehouse matches. I hope they find some. I'm not looking forward to patching up ...

Hi all, Had a good night's sleep so woke up with a clear head. Thinking about the overflowing carbs, there is only one logical explanation: the floats. There's the petcock, if that were the problem, all four carbs would suffer. Float valve seats and needles looked wrecked (with mangled O-ring), were...

Hi guys, "You didn't mention, if you bought original Mikuni 22.5 idle jets. So I assume you're still using the parts of unknown size?" I did mention but I think you missed it. Here's the whole story. I bought the bike as a non runner in 2014. The guy had had the bike running but drained th...

Hi all, It has been a couple of rain filled days since the last update. I ordered original Mikuni parts for the carbs: air jets in size 1.3 and complete float valves, consisting of seats, needles and O-rings. Mounted everything today so the carbs are now back to original specs/parts, apart from the ...

Hi MK, To answer your question: no the new jets don't carry the Mikuni stamp nor the 22.5. Some people also PM'd me so now I have a couple of options to get new O-rings (original, good ones). So there is light at the end of the tunnel. Will try to get a measurement on the old O-rings tomorrow and se...