Rough running
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Andy Pickering
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- Posts: 2172
- Joined: Sun Jan 25, 2009 10:15 pm
- Main scooter: GP
- Location: Hull
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I wouldn't expect the brand new jetex to be faultless as a few lads have had problems with new ones...hopefully yours is fine but just bear in mind muffster ..
Ricspeed, gone but never forgotten RIP my friend #59
TBH if you are getting a good tickover and nice acceleration but poor flat out performance it could be just your main jet that needs looking at. As a precaution with a jetex carb, I would fit a new carb kit. You'll see the difference in quality of the jets / atomiser / float needle etc and it should cure most jetting issues.
Use the link below to help you fit your new parts. I would start with the standard gp200 jetting as this would be a great place to start esp with a nearly rebuild motor that'll need running in.
As for where to buy your spare parts please use a well respected dealer, there are a few on here if you ask nicely. They will also be able to advise too. Try to avoid ebay.
http://www.lcgb.co.uk/workshop/workshopcarburettor.html
If you think you've fitted the incorrect airbox or air scoop etc please take a pic and post back on here.
Use the link below to help you fit your new parts. I would start with the standard gp200 jetting as this would be a great place to start esp with a nearly rebuild motor that'll need running in.
As for where to buy your spare parts please use a well respected dealer, there are a few on here if you ask nicely. They will also be able to advise too. Try to avoid ebay.
http://www.lcgb.co.uk/workshop/workshopcarburettor.html
If you think you've fitted the incorrect airbox or air scoop etc please take a pic and post back on here.
take your air scoop off, the one under the seat. see what its like like that . if it runs ok, its easy to modify the scoop to suit.
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muffster
- registered user
- Posts: 116
- Joined: Sun Jul 24, 2011 5:41 pm
- Xbox live gamer tag: muffinator233
- Main scooter: LI 125 S3
- Location: Bradford
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Hello again folks.
So, checked the timing today and i think it was set at 19 deg. So i changed it to 21 and moved the stator around so the the 2 marks lined up with the 2 marks on the pick up box.
Tightened the stator back up and strobed it but the arrow was still aligned with the 19 deg mark which confused me!!!
I will go and speak to Gary this week and get a carb kit.
cheers.
Muffster
So, checked the timing today and i think it was set at 19 deg. So i changed it to 21 and moved the stator around so the the 2 marks lined up with the 2 marks on the pick up box.
Tightened the stator back up and strobed it but the arrow was still aligned with the 19 deg mark which confused me!!!
I will go and speak to Gary this week and get a carb kit.
cheers.
Muffster
Ignore original timing marks on flywheel by the pickup They are rarely correct and or only used to put the timing somewhere near to running.
Set your own TDC mark opposite the flywheel arrow, then make a second mark to the left of this 2mm of piston travel, that's somewhere around 27mm on the mag housing, This is your strobe light mark (this should align when your engine is run and a strobe light aimed at this mark)
But don't bother with the marks supplied on the electronic flywheel which are set opposite the pickup, or any original marks from a previous flywheel/maghousing, Always check, then where necessary make your own.
Set your own TDC mark opposite the flywheel arrow, then make a second mark to the left of this 2mm of piston travel, that's somewhere around 27mm on the mag housing, This is your strobe light mark (this should align when your engine is run and a strobe light aimed at this mark)
But don't bother with the marks supplied on the electronic flywheel which are set opposite the pickup, or any original marks from a previous flywheel/maghousing, Always check, then where necessary make your own.
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muffster
- registered user
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- Joined: Sun Jul 24, 2011 5:41 pm
- Xbox live gamer tag: muffinator233
- Main scooter: LI 125 S3
- Location: Bradford
- Contact:
Ok mate thanks for that.
The mag flange already has a mark and after checking the arrow on the flywheel lines up with this at TDC.
I must admit i was confused by stickeys book which says when strobing if the timing is clockwise of the mark then turn the stator anti clock and vice versa etc. But then surely the two marks on the flywheel would never line up with the pickup.
Not sure what you meant by- then make a second mark to the left of this 2mm of piston travel ?
Is it best to use a timing disc or measure with string/ruler.
Thanks.
Muffster.
The mag flange already has a mark and after checking the arrow on the flywheel lines up with this at TDC.
I must admit i was confused by stickeys book which says when strobing if the timing is clockwise of the mark then turn the stator anti clock and vice versa etc. But then surely the two marks on the flywheel would never line up with the pickup.
Not sure what you meant by- then make a second mark to the left of this 2mm of piston travel ?
Is it best to use a timing disc or measure with string/ruler.
Thanks.
Muffster.
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onefortheroad
- registered user
- Posts: 148
- Joined: Wed Feb 11, 2009 7:35 pm
- Main scooter: Li125 series 2
- Location: Hull
- Contact:
Jetex carbs are notorious for either working fine or not working at all.
It is recommended that all jets are exchanged for genuine Dellorto ones as a minimum!
I spent ages trying to set one up, then trying to get a couple of old dellortos working that both had stripped choke threads before buying another Jetex that worked well.
One thing I would say is the sticker on the airbox screw saying number of turns out was way off and I had to at least double this!
It is recommended that all jets are exchanged for genuine Dellorto ones as a minimum!
I spent ages trying to set one up, then trying to get a couple of old dellortos working that both had stripped choke threads before buying another Jetex that worked well.
One thing I would say is the sticker on the airbox screw saying number of turns out was way off and I had to at least double this!
To be honest.........stick with the 19 degrees timing.... going to 21 degrees isn't going to cure your problem its just going to make it run hotter.
Sounds like carb to me. If its lacking power on full throttle put a bigger main in , say 5 sizes more than you have currently in it (if you have 122 go to 127 or 128) and if this makes it worse or no better try 5 sizes down and see what difference this makes. Go bigger first just in case its running week.
You cant just buy a carb if the engine is modified that will work properly on standard jets.
Sounds like carb to me. If its lacking power on full throttle put a bigger main in , say 5 sizes more than you have currently in it (if you have 122 go to 127 or 128) and if this makes it worse or no better try 5 sizes down and see what difference this makes. Go bigger first just in case its running week.
You cant just buy a carb if the engine is modified that will work properly on standard jets.