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Discussion Starter · #1 ·
bought this polaris with a cracked top and bottom end replaced both but turns out its a scrambler top end to had to make a carb extension. starts and idles great but once in gear dosen't have power or move me until it revs up the it goes to a max of about 10 km. not sure what it is maybe timing maybe the carb extension ?

also the bike is bored .30 over has a custom piston owned the bike for a year still haven't driven it and i have already put $1000 into to it with no progress please help
 

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Does it rev up in neutral?? If so it sounds like a drive problem, like a belt.
 

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Discussion Starter · #4 ·
is there anything else that would cause this problem ? ill have a look at the belt tonight let you know what it looks like ill even throw up some pictures if it helps
 

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They did use two different jug styles back in the older style 400's, if you were able to get a PROPER intake boot , that shouldn't be the problem.
IF you have the piston in correctly.
While you are looking at the belt, jack up the back axle and start it up and watch the clutches operate, the front should start to squeeze in first, then rear should start moving. at idle , the rear clutch should be squeezed in and the top of the belt should be level or a lil above the top of the pulley.You may need to apply the brake a lil, to start some drag on the engine. Sometimes the lil nylon buttons inside the rear(driven) clutch get too worn down ,which causes the helix to jump over , causingthe inner spring lose it's tension, which kinda causes the symptom you're talking about: no low end
1 and 1/2 turns out on the fuel screw,float tangs parallel with bowl, good fuel flow at the carb.
 

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I'm thinking the rear clutch also.
 

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Discussion Starter · #8 ·
They did use two different jug styles back in the
1 and 1/2 turns out on the fuel screw,float tangs parallel with bowl, good fuel flow at the carb.
by fuel screw you mean on the carb ? and what are float tangs sorry never heard this term
 

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I'm thinking you knocked the buttons off in the rear clutch.You rev it up but it doesn't want to move 'til higher RPM's, right??? If you use lo it works better? Kinda has a skipping sound?
 

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Discussion Starter · #10 ·
I'm thinking you knocked the buttons off in the rear clutch.You rev it up but it doesn't want to move 'til higher RPM's, right??? If you use lo it works better? Kinda has a skipping sound?
yeah however there is no low on this bike just forward and reverse but once it revs up it goes but from 0 to 1/4 throttle wont move and in reverse it worse and my card only have an air adjustment no fuel.
 

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From the last picture it looks like your belt is sitting to low
in the driven clutch. First need to measure the width of the
belt with a veneer caliper. Specs are as follows- Belt Width:
New 1.174 - 1.188" (2.98-3.02 cm) Wear Limit 1.125" (2.86 cm).
Check it at several locations. Inspect belt for hour glassing
(extreme circular wear in at least one spot and on both sides
of the belt). Hour glassing occurs when the drive train does
not move and the drive clutch engages the belt. The belt should
ride about 1/16" above the edge of the driven clutch at idle in
neutral. Second check the belt deflection. Pinch the sheaves lightly
together with clamp to prevent the belt from being pushed into the
driven sheave.
1. Place a straight edge on top of the belt between drive and driven
clutch.
2. Push down on drive belt until it is lightly tensioned.
3. Measure belt deflection. Specs-Belt Deflection (Tension):
1 1/8" (2.9 cm) - 1 1/4" (3.2 cm)
Also, measure the drive to driven clutches center to center distance.
Clutch Center Distance - 10" +.1 / -.05 (254 +2.5 / -1.3mm). And I
agree with RENO & 4getful that your driven clutch has problems.
Note: Clicking on the "Post Reply" button will give the option to add
pics to your post. Buddy
 

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Discussion Starter · #14 ·
so if the driven clutch has a problem how could i fix it or would i just replace it. i know the clutches are quite expensive.
 

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I've had to find some myself.Look on Ebay. I now have a full setup for mine for under $200! Don't get in a hurry and hunt around. I really think your driven clutch is the problem.(rear)(that is usually the cheaper of the two!).
 
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