Fuel Problem maybe more.

[awisewon]

Ok Here is the problem. I replaced the old Chaparral 484cc engine with one that came from a snowmobile. 1st problem was the replacement engine had the clutch shaft on the wrong side. rather than tear into the newer replacement engine to fix the old one. I decided to just install the new engine in backwards. so now the exhaust is in the rear instead of the carb. and carb now in front. The Problem is the new engine starts as long as you spray fuel in it. but dies. if you keep spraying fuel in the carb it keeps running. had a 20 to 1 oil mix thought that was it but nope went to 32 to 1 maybe 40 to mix still same issue. The Fuel pump has two bottom line one top the top feeds the carb, the bottom two the right comes from engine the left from fuel tank and is mounted on rear drivers side back wall. 1st question being are the lines connected properly which I think they are or the old engine would have never started and ran which it did it just blew the head off from stripped head bolds after rebuild of last owner. that all said i know the carb worked properly before and the fuel pump but just in case i opened them both up made sure they were clean and fresh gas it had been stored with no gas in it I had drained it before I stored it. So i am wondering the clear plastic in the fuel pump seems a little bit wrinkled. my line to the carb now instead of just a few inches away is now over a foot away. Am I looking at a line to long issue and its not pumping fuel to the carb? Or am i looking at a Fuel pump issue which means it needs rebuilt or replaced which I'd do both replace with new and get the gasket kit and rebuild the old for backup. I am thinking its both the line to far away now and faulty fuel pump problem both any thoughts would be welcome. It also stinks i had to flit the engine in backwards and re-route both carb & filter as well as exhaust, which exhaust kind of worries me because i am thinking it may create to much heat and be to close to plastic body. any ideas there would be helpful to. thank you all as always you folks are all always helpful and kind.

[wedge]

OK this is tuff with out seeing it but lets try. First off the one line on the fuel pump is the Sence line or Pulse line . It go's to the crank case and that line should be Short as you can get it. ( better pump pulse)
Second: You may have a Bad Crank seal ! This will keep it from pulling fuel through the motor To check this you see if the crank case hold vacume .
Good luck and keep us informed.

[ARGOJIM]

It's a shame you went through all that custom work, on most 2 strokes the jugs can be spun 180 degrees. Check for vacuum leaks as mentioned above, silly question, is your fuel valve on? Also is this an axial fan engine or free air engine (no fan built in )?

[wedge]

X2 ! Jim is rite on this as 90% of the two stroke motors can have there Jug's spun !
i DID IT ALOT ON THE YAMAHA kt100's for racing karts.

[Don]

You may find that you'll have to turn the piston 180 degrees on the rod as well, to keep the rings intact.

[awisewon]

Thanks Don, we suspected you could turn the jugs just wasn't real sure on that one and wanted to be sure the engine ran before time expired to return it as being defective. Plus i don't have a ring tool right now its on the to get list come payday. Thank you.

Thanks wedge we suspected the jugs could be turned its been over 35 yrs that I worked on 2 strokes and I had thought they could be turned and figured being the chaparral engine was used in so many things it just seemed logical to me that everything they ran these engines in would not have the clutch on the same side and the only way to have a quick cheaper resolve to that would be to make the jugs with the ability to be turned 180 or manifolds reversible and given the blot patterns where different I knew right off the exhaust manifold could not be switched. Which was why I opted to put the engine backwards.

You may find that you'll have to turn the piston 180 degrees on the rod as well, to keep the rings intact.

Question being we have custom installed this engine already if we do not turn the jugs and pistons 180 degrees will it harm the engine the way we currently have it configured?

It's a shame you went through all that custom work, on most 2 strokes the jugs can be spun 180 degrees. Check for vacuum leaks as mentioned above, silly question, is your fuel valve on? Also is this an axial fan engine or free air engine (no fan built in )?

There don't appear to be any leaks. free air the old engine has a belt air fan on it was going to look to see if it could be attached to this engine just hadn't got that far along yet have been more interested thus far in getting fuel issue resolved so it would stay running.

OK this is tuff with out seeing it but lets try. First off the one line on the fuel pump is the Sence line or Pulse line . It go's to the crank case and that line should be Short as you can get it. ( better pump pulse)
Second: You may have a Bad Crank seal ! This will keep it from pulling fuel through the motor To check this you see if the crank case hold vacume .
Good luck and keep us informed.

What would be the best way to tell and test a bad crack seal and see if it holds vacuum what tools would be needed to test vacuum?

[awisewon]

Just to be sure this is right. It seems logical to turn the jugs 180 degree and in doing so the pistons also need to be turned as well to keep them and the rings protected. That would solve any heat worries from the exhaust maybe melting any of the plastics. and basically the engine would be installed with the same configuration as the old no mods to exhaust pipe or carb. My question then would is there a head bolt order and certain torque on each bolt. i was taught yrs ago when you don't know just start in the center and rotate side to side and just tighten a little tighter than spark plug tight that sound right. check for leaks and good compression which is c currently 120 on both sides, or are there specs to follow I do have a torque wrench just hadn't used or done major engine work in many, many yrs. Being we now know the engine runs an stays running so long as we keep spraying fuel in it, I'd rather the engine be setup as it originally should be. I can make a Suppressor Tool out of a tin can and hose clamp did a few Bikes that way in my younger yrs just gotta be careful of the sharp can and lube well and ease it in the cylinder and back out so I wouldn't have to wait to buy a ring suppressor tool. But still wondered if the current configuration would harm the pistons and rings seems we do have heat issues solved from exhaust and air filter issue solve for carb leaving only getting the fuel issue so I wouldn't have to tear into this engine. Being I now have a drill press and the old engine is out I can install time certs instead of helicoils in the stripped two bolt holes on the head and re-install that original engine back in it. I had done a few motorcycle heads with helicoils one had 4 bolts stripped it worked fine never had a problem with them only had problems with oil cases that had helicoils because they just had shallow holes to begin with and smaller bolt holes and I think only one of them failed and ended up I had to just buy a whole new lower case and tear the bottom end off that engine if I remember right.

[Don]

Leaving the jugs and pistons the way they are should be fine. The only thing I wanted to point out was that if you rotate the jug, the piston should be done as well. If you post the make/model of your engine, there is most likely someone on the list that has a manual and can tell you the torque and sequence for tightening: there are a lot of us that have played with two-strokes for a long time

[ARGOJIM]

Whoops, looks like I started something.

To check the fuel pump you could manually pulse the pump with your mouth. Before you do that though disconnect all the lines and blow in each port, 2 should have no resistance and one should have obvious restriction. Also with feed line disconnected if the pump is lower than the tank fuel should run out semi freely.

[awisewon]

Leaving the jugs and pistons the way they are should be fine. The only thing I wanted to point out was that if you rotate the jug, the piston should be done as well. If you post the make/model of your engine, there is most likely someone on the list that has a manual and can tell you the torque and sequence for tightening: there are a lot of us that have played with two-strokes for a long time

I can only assume this G50B came out of a 78 Rupp Rally it was sold to me as a vintage NOS Snowmobile engine I can get the Numbers off the tag if that is helpful. The Engine runs fine I just have it in the Attex Backwards so it has no muffler because that engines exhaust manifold was on the rear instead of front. I know that the 78 Rupp Rally was the only S/M with the G50B engine in it and olny 1850 of those Rupps were made before they shut down. I may have a line on a cylinder & Head for my old engine. which if so and the price is right that is all I need to put the original motor back in it. Then I'll have a perfectly good running spare engine but will need Exhaust manifold y pipe for it and a carb & carb gasket set and rubber boot, and muffler to have 2 perfectly running G50B engines just the SM engine has the Shaft for the clutch on the wrong side for the Attex as it currently is. Thanks for the Help you folks are always great.

Whoops, looks like I started something.

To check the fuel pump you could manually pulse the pump with your mouth. Before you do that though disconnect all the lines and blow in each port, 2 should have no resistance and one should have obvious restriction. Also with feed line disconnected if the pump is lower than the tank fuel should run out semi freely.

Yeah I did that nothing blew out any hole opened it up to see if it was clogged found nothing. Run compressed air through the gas cap to see if gas line was clogged it was fine hooke up gas line to pulse pump gas came out one hole but not to easy. and when all lines were connected nothing cam out so I suspect the pulse pump needs rebuilt. I ordered a 12 volt 3 to 7 psi electric universal fuel pump and will order a new pulse pump and repair kit for the old one. But I attached a small gas tank gravity fed it starts and runs just fine drove it around a good bit all worked and ran fine.

Leaving the jugs and pistons the way they are should be fine. The only thing I wanted to point out was that if you rotate the jug, the piston should be done as well. If you post the make/model of your engine, there is most likely someone on the list that has a manual and can tell you the torque and sequence for tightening: there are a lot of us that have played with two-strokes for a long time

I would have to rotate the Jugs and pistons to run that Rupp Rally Engine in the Attex to hook up exhaust pipe to get to muffler you need a true 90 degree coming off the manifold part of the exhaust pipe unless I can find another manifold for the rupp engine cause I am not hacking on the one that came off the original engine. But we tried making pipe to get to the muffler 2 90 degree turns it wouldn't even start but for 2 mins with no power. My buddy kept saying it was the carb. I knew 2 strokes were funny like that if the exhaust pipes aren't properly tuned which is hard to do or make in the back yard. So I disconnected that crap run just the Straight Pipe which then I can't put the hood & rack back on like that not going to cut in holes in it either to make it fit push came to shove I'd make a whole new hood and seat for it before I'd do that. But have I disconnected the rigged exhaust it put the straight pipe back on it started and ran fine again. So until I either turn the jugs an pistons on the Rupp engine I just have to run it with straight pipe and no hood or seat, or get the cylinder replaced or fixed for my old engine. But well get it going right here just time and a bit more money.

Just wondered to will the Chaparral 440 exhaust manifold fit the G50B engine cause I can get a good deal on one and that would solve the exhaust system issue with this Rupp Engine because we could weld pipe to route to the muffler then to I wouldn't have to mess with my original engines exhaust manifold which I have temp installed on this Rupp engine. In fact a better quest if anyone knows what other model, make engine parts if any interchange with this G50B engine.