jabcb wrote:
Rubber Renue by MG Chemicals does a pretty good job of softening carb intake boots and making them usable again.
Never heard of this stuff. Do you know where it can be purchased at? Is there a website?
A heat gun makes carb boots nice and soft, but as soon as they cool, they go right back to rock hard.
76 GT500 - restoration project in work
4 other 76 GT500's
1.5 GT550's
4 GT380's
5 T500's (72-75 models)
4 GT750's
Suzuki GT hoarder...and a bad case of OBD.....(old bike disease)
Their list of distributors is at: http://www.mgchemicals.com/distributors/index.html" onclick="window.open(this.href);return false;
I ordered it from a local electronics supply store that was on their list.
It was something like $10 a bottle and I used something like 1/2 a bottle.
I'm not an expert on vintage bike maintenance. Did a lot of research on the web. Problem is not unique to old Suzukis. Vaguely remember having found this on a vintage Honda forum. The ingredients are pretty common. So some people buy Rubber Renue & some make their own equivalent.
BAS (Bike Acquisition Syndrome) - too many bikes but have room for more
British bikes have always been 4 strokes with a dry sump type of oiling. That is why they have a 'suction' valve to keep the oil from back flowing from the oil tank. Virtually all the 2 strokes they made were pre-mix only. These check valves wew are referring to keep the oil in the lines from draining into the crankcase when the engine is off. When it is running, the pump forces the check valve to open to inject just enough oil to do the job.
yeah oddly enough i have seen a 2 stroke before. And if there is no air leak, a suction valve would work as good as a pressure valve. But if either system has a leak the results are equally bad. The suction valave in a british bike has enough pressure to keep the oil from flowing until the pump draws even slightly, opening the finely balanced valve. If this valve is closed oil still cannot drain from the line, its like a straw full of pop. It cannot work with a leak on the suction side, nor can the pressure opened valves on the banjo fittings. if the system is stopped at any point, oil stops flowing. And the sole purpose is to prevent case flooding in both systems. I fail to see a difference in either method of flow control.
There is no "suction" side in a GT750 oil pump after the J model. They removed the third plunger.
There are two plungers feeding 6 oilways and each has a blow off or check valve to stop the draining effect. They are very light spring type ball valves with 1-3psi blow off pressure.
rbond wrote:British bikes have always been 4 strokes with a dry sump type of oiling. That is why they have a 'suction' valve to keep the oil from back flowing from the oil tank. Virtually all the 2 strokes they made were pre-mix only. These check valves wew are referring to keep the oil in the lines from draining into the crankcase when the engine is off. When it is running, the pump forces the check valve to open to inject just enough oil to do the job.
A quick question; I thought that these check valves also kept the positive charge in the crankcase from pushing the oil back into the line, as well as to keep the oil from entering the engine when off.
A quick question; I thought that these check valves also kept the positive charge in the crankcase from pushing the oil back into the line, as well as to keep the oil from entering the engine when off.
Yes, that's definitely another function performed by the check valves.
A single valve on the pump suction side would work quite well......IF it wasn't for the positive pressure pulses from the crank chamber.
The pump itself is a positive displacement device....BUT.....it does have a lot of internal clearances (on the ones I've had apart) and without the check valves on the crankcase side, I believe that it would be quite easy for the pressure pulse(s) to force the oil back through the pump. My understanding of all the nuances of the system is less than perfect, so......
What we need here is a well thought out but simply stated/easily understood paper on the whole system as built back in the day with all facets of operation explained. Since we don't have Kevin Cameron as a board member, I vote for a lengthy submission from JA on this subject. He's a very clever man who understands two strokes quite well. All in favour of JA doing a thorough writeup on this subject raise their hands....
GT550A Mint & Original
H2A Semi-Hot Rod Built From A Basket Case
KZ650C2 Mint & Original...mostly
GSF1200SK6 Bandit...My LD Ride
Additional H2 projects In Boxes.....
MBD Sufferer
I'm not JA so I'll give you the short version. If you want to know about pumps, pop over to http://pinkpossum.com/GT750/Oilpump.htm" onclick="window.open(this.href);return false;
The banjos are really simple one way valves. Apply positive pressure from the pump towards the motor in the direction of flow and you can hear and feel them pop open at 1-3psi. Apply pressure against the direction of flow and they should remain closed.
" Virtually all the 2 strokes they made were pre-mix only." This was in my original post, so I did in a roundabout way mention The Scott (drip feed). The Banatam as far as i know, was a pre-mixxer. I will check on that one.......
,,,,, you forgot the Scott Squirrel and the BSA Bantam, Brit two strokes all the way.
