zdw0889

Just got this 4 wheeler on a trade. Its a 96 honda 300 ex bored to a 350? And big bore carb kit. Guy i got it from said he could only get it to run for two min and plug would foul. He had the choke on. Anyways it runs but falls on its face when you punch it. But it will still get up just not nearly like it should. I know nothing about these machines. Need help please

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96 polaris ultra sp 680 dg can cobra windshield, 89 el tigre ext 530, 98 zr 600 efi, 80 yamaha exciter 440 l/c, 96 cougar 550.

smallengineguy

Have you checked to see if the carb was clean?

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1992 Ski Doo Mach 1 (SC-10/2 suspended) March '07 SF.com Sled of the Month! (Lost in fire 4-7-13)
1992 Ski Doo Mach 1 original
2006 Ski Doo MXZ 500SS
1999 Ski Doo Grand Touring

Webmaster Evergreen Valley Snowmobile Club
SledNH.com Moderator

kccats

And if all the right jets are in the carb!

zdw0889

I'm getting the carb looked at tomorrow to make sure everythings ok and to get it tuned right. And see if that makes a difference. Its got low end power just not top end

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96 polaris ultra sp 680 dg can cobra windshield, 89 el tigre ext 530, 98 zr 600 efi, 80 yamaha exciter 440 l/c, 96 cougar 550.

zdw0889

And carb looked ok but then again i didnt take it off to inspect it

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96 polaris ultra sp 680 dg can cobra windshield, 89 el tigre ext 530, 98 zr 600 efi, 80 yamaha exciter 440 l/c, 96 cougar 550.

smallengineguy

It can look fine on the outside, but the inside can be trashed.

__________________
1992 Ski Doo Mach 1 (SC-10/2 suspended) March '07 SF.com Sled of the Month! (Lost in fire 4-7-13)
1992 Ski Doo Mach 1 original
2006 Ski Doo MXZ 500SS
1999 Ski Doo Grand Touring

Webmaster Evergreen Valley Snowmobile Club
SledNH.com Moderator

kccats

Even if the inside looks good doesn't mean anything either! If it was rejeted who knows what is in it! Read the numbers on the main and pilot jets.

zdw0889

Took it out and cleaned very good. Jets were almost completely clogged. Put it back on. A lot more power!

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96 polaris ultra sp 680 dg can cobra windshield, 89 el tigre ext 530, 98 zr 600 efi, 80 yamaha exciter 440 l/c, 96 cougar 550.

zdw0889

Not 100% sure cause i dont have the jets in front of me but it was k420 or somethin like that.

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96 polaris ultra sp 680 dg can cobra windshield, 89 el tigre ext 530, 98 zr 600 efi, 80 yamaha exciter 440 l/c, 96 cougar 550.

zdw0889

So ran good for like 45 min the all the sudden boom no power wont even stay running. So took off the carb jets were clogged. Cleaned them. Inspected the tank. WOW dirty. Had spots of rust in it. Cleaned it out best i could. Changed oil and oil filter put new plug in. Just need to go grab some gas and hope it lasts longer. I have a feeling i will have to repeat this a few times.

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96 polaris ultra sp 680 dg can cobra windshield, 89 el tigre ext 530, 98 zr 600 efi, 80 yamaha exciter 440 l/c, 96 cougar 550.

kccats

I have a similar prob with a Kawi bike! You may need to get some Fuel Tank Coating?

zdw0889

Got a longer run time still running decent. But top end still seems a little sluggish til 3rd gear. Do you think the top end could need replaced? Tried to get a compression tester for it but it would have to be ordered and was expensive. So ill wait on that. Where do i get gas tank coating? Auto parts store?

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96 polaris ultra sp 680 dg can cobra windshield, 89 el tigre ext 530, 98 zr 600 efi, 80 yamaha exciter 440 l/c, 96 cougar 550.

aduck

Standard compression testet will work fine. Bout 25 bucks at any auto parts store

Sent from my M865 using Snowmobile.com App

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93 mach1 670
02 rmk 800 162
95 powder special 580

mr.deeds

You can buy that tank coating at Rocky Mountain atvmc (i've seen their adds on this forum... and good prices) and Dennis Kirk would have it. I think its called Creme-- I used it on a rusty tank and it fixed the problem pretty good. You do want to have it as clean as possible before you do it. I would also put one of those little in-line fuel filters on- just to help a little more.

zdw0889

Aduck i have a standard tester wrong size wont fit. And yea when i cleaned the carb the second time i used a inline filter

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96 polaris ultra sp 680 dg can cobra windshield, 89 el tigre ext 530, 98 zr 600 efi, 80 yamaha exciter 440 l/c, 96 cougar 550.

aduck

Are you missing the other fittings. I use mine on my 400ex and 450 as well as the sleds no issues

Sent from my M865 using Snowmobile.com App

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93 mach1 670
02 rmk 800 162
95 powder special 580

zdw0889

Can i hold my compression tester on there with someone trying to start it and get a good reading. My tester only came with one extra fitting

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96 polaris ultra sp 680 dg can cobra windshield, 89 el tigre ext 530, 98 zr 600 efi, 80 yamaha exciter 440 l/c, 96 cougar 550.

kccats

I think I still have the reducer fitting that came on one of my testers?

yamadad4

another thing to consider is fuel tank venting as well as carb vents.

your issue almost sounds like the tank isnt properly venting and creating almost a vapor lock situation.

if your carb is equipped with a vent line on the upper portion, same issue can occur if this line is plugged.

zdw0889

The gas tank vent is just the hose coming off the cap right? If so i replaced that cause there wasnt one. Ill have to check out the carb next time i take it out for the vent lines. And kc dont wanna take your extra might need it some day ill buy one if i can find it.

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96 polaris ultra sp 680 dg can cobra windshield, 89 el tigre ext 530, 98 zr 600 efi, 80 yamaha exciter 440 l/c, 96 cougar 550.