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Discussion in 'Motorized Bicycle General Discussion' started by donutguy, Jul 14, 2011.
Looks ok,but dont know if its the exact same engine as the monster....
Well, I got my Gt50R back from thatsdax and it still will not start. My opinion of these engines are definitely heading in the negative direction.
Hmmmmm, I had absolutely no problems with mine....are you using the choke?
I tried with the choke on and off. I checked for a spark. I changed the spark plug. I checked the fuel lines for flow. I took apart and cleaned the carb. I sprayed starter fluid in the carb. I tugged and tugged on that rope and no start. If you got any other suggestions, I try it.
Sorry, I'm not much help.....while I am somewhat mechanically inclined-diagnosing 2 stroke motor problems isn't my strong suite.
I know the basics and that's about it.
I know they have a centrifugal clutch......maybe roll it a down a long hill and go fast enough for the clutch to engage the motor-give it some gas and see what happens.
what is a ddm code?
Unfortunately, a friction drive does not work that way. The engine has to be running in order for the clutch to engage. sssssssssssssss
Check the coil air gap.
Sounds like you have no spark to the plug....or maybe a timing issue which is probably unlikely, but always possible.
Yes as John the Chimp mentioned check that the gap between the coil and the flywheel is about the distance of a bank check, this is a good distance on most small engines IMExp.
If starting fluid gets zero response then I say you have an ignition ploblem.......
bad wire? bad plug? bad coil? kill switch wire grounded? air gap between coil and flywheel to wide? check all of these and see what you end up with.
Make sure all engine bolts & nuts are tight and all gaskets are sealing good also, cant be any air leaks on a 2 smoker.
I own a Subaru Robin EH035 & just sold my Lifan 2.5 (98cc). I recently got the identical engine to the GT50R but sold elsewhere & have been putting miles on it. Before I come up with a full review I wanna make sure I dont blow it up. Aside from having to red loctite the headbolts (were getting loose) & venting the fuel cap, the engine has been a blast to ride & starts on the 1st pull. The Subaru Robin bike is nicknamed 'Wimpy' & tops out in the low 30's & slows down when the wind blows. This 'Little Screaming Monster' is barely at half throttle in the low 30's & has so much more to pull (powerband hasn't been tapped into yet). I got it geared @ 15.6:1 now without an expansion chamber (coming this Tuesday) & it hits low 50's & pulls off the line better than the Suby. I honestly believe with the correct gearing it could do in the 60's (mph). If durability holds up, it will be the best $129 I ever spent & I will buy another. I would then considering selling my super reliable Subaru Robin in the Swap & Shop. Guess I've turned to the 2 Stroke 'Dark Side'...lol
Yeah.....like I said.....I ain't an expert
I have two of these engines from different vendors,both would run great until I shut them down and let them cool down then they would not start, both had loose head bolts.
Yes, Head bolts on these engines are the weak link.
Mine got loose after my 1st ride & good thing I thought to check them out.
The way I did it was to remove one, use Red Loctite on the threads, then tighten it back up nice & snug before removing the next one for the same treatment & so on.
I also was getting loosening of the spark plug. I removed it, checked the gap, & used Blue Loctite on just the threads closest to the spark plug gasket...All have remained tight since.
Another buddy of mine just blew his Stage 3 engine on the 2nd day of ownership due to loosening head bolts....This seems to be the achilles heel of these pocketbike engines...
Red Loctite worked for a few rides, but I took it out for a speedy ride yesterday & sure enough, one of the headbolts loosened up & I could hear that compression escaping sound (It helps that my engine is in front of me to easily keep on eye & ear on her).
I decided to remove the headbolt & head on down to my local Lowes hardware store.
The size of the bolt is M6 X 1.0 X 80mm. I didnt find anything @ Lowes but found 90mm bolts @ McMaster Carr & ordered a bag of 10.
I'm hoping the extra centimeter length grabs more thread in the engine & doesnt loosen as easily.
The engine revs so high that bolts will vibrate loose. I guess its inevitable & probably the cause of many of this type engine failures when gone unchecked. I want to order a 2nd engine just like this one I got, but want to solve the 'Mystery of the Vibrating Loose Headbolts' 1st...
Bought another Stage 2 engine & built up another bike. As soon as the engine arrived, I replaced the head bolts with the longer ones & did the red Loctite & 2 lock washers per bolt. Just out today on its maiden voyage taking it easy on the engine for a few miles. I think the base gasket on the 1st engine shot since I was able to pull away some paper under the engine. I ordered a .020 copper gasket for $10 from Pocket Bikes Unlimited today & once it arrives, will replace the gasket before taking that engine out for another ride. The power these puppys make truly is amazing and the gaskets & bolts may be the weak link here.
Actually....I've sent both my motors back and am in the process of getting a refund.
Too many problems for me....the new motor thatdax has coming out with the one piece head is a really nice motor, been using it for the past week or so.
Have you noticed any difference in power between the two engines?
Just curious in case I need to go down that path in the future.
Perhaps the case engineering & head bolts issues are due to the increased stress from the higher compression dome heads?
Maybe, just a smidge less power and low end torque. You have to keep in mind that I am quite content to cruise at 20 mph. While I did quite like the extra power reserve of the GT 50 R, it just wasn't reliable enough for me.
The new engine still has enough grunt to get me up over some of the hills we have here in Southcentral PA.....
I glad you were able to get your money back....What exact new engine did you buy from DAX????
I love my GT5R, once you've worked all the factory bugs out of them they are very reliable, the copper head and base gaskets and the after market studs, lock washers and blue loctite upgrades are a must.
Also ditch the CNS carb and use a DellOrto SHA or Grubee speed carb. The CNS just wasn't tested properly, and I cant seem to find a tuning manual for the CNS carb... wtf?
We need to all jump on the manufacturers and get them to test the new stuff better, get a handle on quality control and for Pete's sake print instruction manuals.
If there was an American made equivalent to the China Girl, thats what I'd be running.
Morinis are nice but there heavy, expensive and it takes forever to get parts for them and tune them right and they make to much power for shift kits.