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Post by nimbus on Feb 24, 2014 9:05:00 GMT 1
Hi guys Why is it the same cylinder every time. Have cleaned carbs main jet 260 pilot 25. Now what? Had her on the local race track (Scribante Port Elizabeth )and she seized at the end of the straight on lap five. Please help.   |
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Post by midlifecrisisrd on Feb 24, 2014 9:14:53 GMT 1
Bike?
Carbs?
Pipes?
Filters?
Pump or Premix?
Steve
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Post by Norbo on Feb 24, 2014 9:35:21 GMT 1
do you have cracks in the reed rubbers
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higgsy
Thrash Merchant
Posts: 458
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Post by higgsy on Feb 24, 2014 9:47:36 GMT 1
To break up that badly on the inlet side suggests a couple of things. Is the bike on pre-mix or the pump? It looks dry with signs of lubrication issues. Is there an air leak at the reed joints? Cracked inlet rubbers or leaking gaskets. It could also be a head gasket issue, if it's leaking the symptoms can be the same as an inlet air leak
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Post by muttsnuts on Feb 24, 2014 9:56:17 GMT 1
air leak, check your crank seal on that side, reed block rubbers, barrel and head for cracks, if running a boost bottle check for cracks in the welds etc, also check the faces of the head and barrel to make sure they are flat and seal correctlty, also when fitting the barrels you should ALWAYS check that the base gasket of one of the barrels is not sat under the other otherwise you end up with one barrel sat slightly proud which allows it to suck air in
If all else fails, get the engine assembled again and then pressure test it before fitting/runnng etc to see if you have any leaks
If its none of them then lubrication is an option and the only other thing is a twisted crank, but you'd need to check that carefully
HTH
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Post by nimbus on Feb 24, 2014 12:03:00 GMT 1
Bike 1981 RD350LC 26mm carbs main jets 260 pilot 25 Jim Lomas pipes premix 32-1 Filters foam pods  |
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matt7
Thrash Merchant
Smell of the 2 stroke & the roar of the crowd
Posts: 445
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Post by matt7 on Feb 24, 2014 14:52:02 GMT 1
Is the fuel tap flowing suffient juice for prolonged WOT ?
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Post by arrow on Feb 24, 2014 14:55:33 GMT 1
What side is the problem side?
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Post by wawenwong on Feb 24, 2014 15:43:57 GMT 1
Nice bike btw
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Post by midlifecrisisrd on Feb 24, 2014 17:19:24 GMT 1
I would have thought 260's with pods and Lomas pipes is lean
Probably around 300
Steve
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Post by steeley on Feb 24, 2014 19:49:47 GMT 1
I thought a bit lean,go big and work down.best thing to do get it on a dyno.i had my tuned 350 lc running on 310 mains ,foam filters going down the m5 towards Bristol to a bike meet .I was cashing a mate on his 350 .my bike was so over fuelled my 35 mile trip there and back was done in 4 and 5th gear.what a trip.soon got the 310 out and put some 290s in.
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Post by rich on Feb 24, 2014 19:54:58 GMT 1
I would have thought 260's with pods and Lomas pipes is lean Probably around 300 Steve Agreed |
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peacey
Drag-strip hero
Posts: 271 
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Post by peacey on Feb 24, 2014 20:25:59 GMT 1
Yeah 260 a bit lean I would have thought, what colour are your plugs?
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Post by iang1 on Feb 24, 2014 20:39:24 GMT 1
I would have thought 260's with pods and Lomas pipes is lean Probably around 300 Steve Seconded, I have had problems with pod filters which were only really been properly solved by going back to an airbox. |
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brads
Weekend rider
Posts: 53
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Post by brads on Feb 25, 2014 14:10:20 GMT 1
Bike 1981 RD350LC 26mm carbs main jets 260 pilot 25 Jim Lomas pipes premix 32-1 Filters foam pods You're definitely a fair bit lean and you're running premix which generally would require one jet size bigger too. Also if you are riding on the track I would also add more oil to your premix ration as IMO 32:1 is a little light on the oil..... |
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Post by steeley on Feb 25, 2014 14:17:07 GMT 1
nimbus,what a lovely bike hope you get it sorted soon.
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Post by muttsnuts on Feb 25, 2014 14:22:03 GMT 1
yes, agree with above, checked my notes etc and running foam filters like you are you will need to jet between 290 and 310, running premix as well, so I'd opt for 300 and see what the plugs look like after some running, but get it dyno'd if you can
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Post by rossco on Jun 13, 2015 22:46:08 GMT 1
Check your fuel tap, I had this issue, fuel tap was not shutting off in the 'off' position and when left for a week or so on it's side stand it would fill the left hand crank case with neat petrol, sadly the first I knew of it was a seized engine. Does it take a long time to start after it's been stood for a few days?
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Post by bryan on Jun 14, 2015 3:34:12 GMT 1
Welll it looks like it's well lean buy the top of piston!
If it's the right piston then you could have twisted centre section causing you timming to be too advanced. Thought it could just be a combination of a few slight differences on that cylinder causing it to be the one effected buy your jetting the most.
Always go way over what you think you need with main jay, as your going to be doing plug chops to check mixture, you don't ever want to be doing WOT with a lean mix.
Plus on track WOT down a long straight on a 2 stroke is where it's going to happen.
My YPVS with Gibson pipes, drilled air box lid with no snorkel is on 260s!
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Post by lb on Jun 14, 2015 4:44:05 GMT 1
Very nice LC!Can I ask what JL pipes are they & what tank is that?
Look up Maccas/Dan,he's selling a very nice pressure/vacuum tester kit on this forum.Just used it & worked a treat,priceless to know its right.
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Post by wolfboy1 on Jun 14, 2015 8:53:59 GMT 1
no imput on the running issue , but ............ what a great looking bike ! reminds me of my yell speed block fs1e dx  |
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