tundra with a 503 in it - Snowmobile Forum: Your #1 Snowmobile Forum

vincanety · 12-23-2012, 04:16 PM

I have a tundra which I put a 503 in it and it starts up great no problem runs smooth at idle but as soon I I start going with it it bogs at mid range and top end if tried adjusting the screw for the mixture but I'm not sure what else to try to adjust and what kind of spark plugs am I suposed to be running

**smallengineguy** · 12-23-2012, 07:11 PM

BR9ES plugs. It may be a belt adjustment issue.

vincanety · 12-23-2012, 08:22 PM

Well I'm running the stock tundra secondary with the 503 primary clutch could that be the problem ?

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northerner1212 · 12-24-2012, 05:30 AM

clean the carbs check the fuel line for kinks

**smallengineguy** · 12-24-2012, 06:35 AM

Is the belt deflection good? If the belt is too loose, it won't run/backshift correctly. Clean the carbs as stated above as well.

vincanety · 12-24-2012, 07:37 AM

The carb looked clean when I took it a part but what jets should I be running any way to change the needle position and would the tundra gas pump, pump enough gas or could that be thd problem

vincanety · 12-24-2012, 11:04 AM

K well pretty sure I figured the problen is in the points what are the suposed to be at specs cause one cylinder fireds a clutch side sparks but I'm thinking wrong timming cause the plug is always wet could someone reply to me asap

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vincanety · 12-24-2012, 10:49 PM

Nvm my other posts ill rewrite what Ive tried so far k well plugs firing on the mag side fine but the plug on the primary side is wet there's good compression on both sides and we re adjusted the points changdd the condesator and point on the primary side still no affect we switced the coils around still got the same problem on the same side any info on what to next what to check would be greatly appreciatted and thxs for the help so far

aduck · 12-24-2012, 10:56 PM

Sounds like its in that carb needle/seet most likely not sealing and flooding that side out.

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vincanety · 12-24-2012, 11:05 PM

The engine has single carb so how would that work?

aduck · 12-24-2012, 11:22 PM

That changes it. Sorry. Id get an inline spark tester and check spark. And double check compression on that side

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**RJ Gleason** · 12-25-2012, 05:09 AM

There are two charge coils for the ignition.
If one is bad, you will not get spark on one side.

vincanety · 12-25-2012, 07:31 AM

There is spark on both cylinders same nice strong spark its like If the timing would be off and we switch around both normal coils and we pyt in a new charginv coil still no go bur the thing is we had retimmed it to so I dont know what else it could be
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**RJ Gleason** · 12-25-2012, 10:18 AM

Go back and check your work, possible pinched wire that is now grounding out.

vincanety · 12-25-2012, 10:36 AM

Well the problem was the exhaust we made to fit wasn't thr right back pressure cause my 600 vmax gives me twice the power so got to try and make the stock exhaust fit

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joshkidner · 12-25-2012, 11:26 AM

make the motors exaust fit in the chasis. the pipes especially are made spcifically for the motor. the pipe doesnt much matter too much. it can change the ammount of backpressure though.

vincanety · 12-30-2012, 07:36 PM

K well I figured the problem out it was the exhaust and engine was running a 310 jet for single carb seemed way high so we put a smaller one in ran like a champ so I'm wondering is I got a mikuni carb and I'm trying to order a k&n air filter from royal distributing but can't figure out which air filter I need like what are thd specs for the carb

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