Suzuki 2 Strokes

I did the first run on my GT500 the other day... just a short run and when I came back I noticed that there was lots of air in the left hand oil pipe, and a little in the right hand. After a bit of reading on here, I came to the conclusion it was either the pipes. or the valves...

I did a search on Ebay and there is a company that make the valves, and interestingly they are only 5 miles away! As it was Bank Holiday I knew I would have to wait a few days, so I took the pipes off and took a careful look a them. they seemed OK, looks like it was the valves then...

I read the instructions from the company on how to replace them, and removed them from the pipes, it was pretty easy from their instructions. So I now had 4 valves sitting on the bench. Three of them seemed OK, but one, I could blow through either way in my mouth so I decided to take it apart.

with it clamped in the vice (soft Jaws) I used a pair of pliers to prize it app apart. it actually came apart easily. as I pulled the ball and spring out, the problem was easy to spot... the ball was actually stuck in the spring! I gave the spring a little tweak to stop the ball going back in and assembled it back together by just tapping the end back in.

before I did this however, I very gently faced off the ball seat by carefully rubbing it on some 2000 grade wet and dry on a piece of glass. It didn't take much...

I did this to the remaining three valves (which were actually OK - but it was an opportunity to check them) and put the pipes back on. The result is there is no air or bubbles in the lines any more. Thought I would share this with you guys, just in case no one else has done this! here is a picture of the offending valve, and a link to the sheet from the company that sell them.

http://www.1970sjapmotorbikeparts.co.uk ... ctions.pdf

I see on their eBay ad they say "We recommend that you fit all 6 new valves due to standing or misuse in the past 40 plus years"

I've got a NOS spider that I was going to fit to my rebuilt motor and I havn't got a clue how old it is. Does this mean the check valves could be suspect just through age and not use?

after taking one apart I cant see how they would have been affected by age... its a Brass fitting, a ball and a spring. they are easy enough to get off the pipes, and to take apart to check. I guess the critical bit is the pipes, they seem to go brittle and crack. The ball wedged in the spring was probably due to me using compressed air to blow them out during the rebuild.

If I was doing it again, I would use a plastic bottle of solvent to flush them out, and blow them clear by mouth (with a bit of pipe!) or turn the air right down on my compressor.

That is an interesting example of a check valve failure caused by incorrect cleaning.

The ball is pushed into the spring but should be free of the spring. Cleaning them with compressed air causes the ball to be shot back and pressed into the spring coils and after that it will never seal correctly.

With a 40 year old bike the possibility always exists that a PO used air to try to clean or seat a valve, so they should all be checked or replaced.

tz375 wrote:That is an interesting example of a check valve failure caused by incorrect cleaning.

The ball is pushed into the spring but should be free of the spring. Cleaning them with compressed air causes the ball to be shot back and pressed into the spring coils and after that it will never seal correctly.

With a 40 year old bike the possibility always exists that a PO used air to try to clean or seat a valve, so they should all be checked or replaced.

It is... and it was probably me that did it... I used the airline to blow the old oil out as part of the rebuild

soon as I rode it up the road it was clear there was a problem. It only affected one valve though, the other three were OK. Lesson learned.

I have read that many people replace these, when a strip down and clean, is probably all that's needed. I did clean the face where the ball sits with some 2000 wet and dry though on all of them though... they are all working fine now, no air bubbles at all.

I did think that if I needed to replace the pipes at some point I would just use some clear air pipe and some "T" fittings like these. my local factors sells these in 3,4,5 and 6mm sizes, plus the clear pipe to push in them. might help people who are struggling to find originals.

buzzer wrote: I did think that if I needed to replace the pipes at some point I would just use some clear air pipe and some "T" fittings like these. my local factors sells these in 3,4,5 and 6mm sizes, plus the clear pipe to push in them. might help people who are struggling to find originals.

what is this thing ^ ? My google-fu didn't turn up an image match

A T-connector for compressed air lines

4mm nylon pneumatic tube is pretty close and heat forms nicely. Here's the replacement set I made for myself

akendall1966 wrote:4mm nylon pneumatic tube is pretty close and heat forms nicely. Here's the replacement set I made for myself

Fantastic! how did you make the junction pieces?

lots of these fittings in Amazon @ Industrial & Scientific -> Hydraulics, Pneumatics & Plumbing -> Fittings -> Tube Fittings -> Push-to-connect Fittings

looks like they run about $3 to $5 with various in-line or T options available.

how much line pressure does the GT pump produce?

MikeD wrote:lots of these fittings in Amazon @ Industrial & Scientific -> Hydraulics, Pneumatics & Plumbing -> Fittings -> Tube Fittings -> Push-to-connect Fittings

looks like they run about $3 to $5 with various in-line or T options available.

how much line pressure does the GT pump produce?

I would say the pressure in the pipes is negligible.... these Pneumatic pipes and fittings can stand hundreds of PSI. the push fittings are great as well, just make sure you cut the pipes cleanly with a knife.

buzzer wrote:Fantastic! how did you make the junction pieces?

Junction are made from 10mm nylon sheet cut into rectangles and drilled tubes are glued in pump line has a piece of 6mm tube glued over the 4mm tube and to the block as strain relief.

Ade

akendall1966 wrote:

buzzer wrote:Fantastic! how did you make the junction pieces?

Junction are made from 10mm nylon sheet cut into rectangles and drilled tubes are glued in pump line has a piece of 6mm tube glued over the 4mm tube and to the block as strain relief.

Ade

Brilliant! thanks for that, I love seeing stuff like this made!

Excellent stuff buzzer.

akendall1966 wrote:

buzzer wrote:Fantastic! how did you make the junction pieces?

Junction are made from 10mm nylon sheet cut into rectangles and drilled tubes are glued in pump line has a piece of 6mm tube glued over the 4mm tube and to the block as strain relief.

Ade

Looks good - what glue did you use to put the 6mm bracing in?

Jim