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LukeBrinkerhoff

17’ 350rr no power when hot

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Just to note random stuff... my 01 cr 250 would boil gas , not run good, with a big tank and it was because of the gas cap not venting. Same with my 525 rs Beta. .. boiling gas and expanding the gas tank. 525 rfs motors have always been known to run hot so a fan and high pressure cap and overflow tank went on along with running water and water wetter.  I just put a fan on every bike I own. That’s a minimum. If I can’t put a fan on big radiators goes on.. to start. ..and systematically add more cooling mods.

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Posted (edited)
29 minutes ago, LukeBrinkerhoff said:

 There’s not a lot of these around me. I think we are on track with the engine heating up the tank.

 

 That’s what I’ve been looking for, someone with the same issue. Thank you! I’ll try it, won’t know when i will. Won’t have parts in time to put it on, and I’ll  be on vacation next week. 

Maybe the fuel pump is cavitating, or vapor in the line otherwise causing  a lean condition.   He also had throttle body problems but that was fixed.  Your video shows pretty wide open course, was it very hot out?  I rode another 350RR at a demo and liked the motor but it was cooler out.  

I have a 250RR but also a YZ250FX.  As a precaution I covered the bottom of the tank where it sits over the head with the reflectacoll stuff, but on the FX the pump is in a lower well in front of the shock (cooler spot).  You can get it on Amazon easy.   I got a big sheet but the tape would have been easier.  

Years ago I also had a Cannondale 440.  That thing was crazy hot with the header  running under the tank, fuel boiled like mad but pump was remote, and it also roasted your left leg.  I ceramic coated the header and it helped a lot.  I might even do mine over the winter as the starter gets pretty hot  from the header. 

 

Edit:. I remember on the 'Dale having running issues from the hot fuel in the HP line further heated by the back of the radiator as it was plumbed to the injectors. It would pop stall and be hard to restart. I fixed this with silicone coated Nomex tubing insulation from McMaster.

Interesting, on the FX, the HP line from the tank/pump to the injector has a thick foam insulator layer the entire length as it crosses over the top of the head.  

Edited by GP
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Got the fan on and put some reflector tape on the tank. I didn’t quite buy enough, I feel like more of where the tank drops down needs covered than over the pump.

4E9CBEE2-B8CE-4BE6-A2FA-4A4E109C5C6A.jpeg

B778C0F7-167E-40A3-AFE8-8B9DF71B7E44.jpeg

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10 hours ago, LukeBrinkerhoff said:

Got the fan on and put some reflector tape on the tank. I didn’t quite buy enough, I feel like more of where the tank drops down needs covered than over the pump.

4E9CBEE2-B8CE-4BE6-A2FA-4A4E109C5C6A.jpeg

B778C0F7-167E-40A3-AFE8-8B9DF71B7E44.jpeg

Hope the fan helps. Should get an overflow tank too.. buy or make... Whatever boils out you want coming back in..

Edited by hawaiidirtrider

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14 hours ago, hawaiidirtrider said:

Hope the fan helps. Should get an overflow tank too.. buy or make... Whatever boils out you want coming back in..

Me too. I wonder what temp the thermal switch kicks on. I’ve got a motion pro one overflow(was actually on it) but did no good since I wasn’t ever boiling.

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1 hour ago, LukeBrinkerhoff said:

Me too. I wonder what temp the thermal switch kicks on. I’ve got a motion pro one overflow(was actually on it) but did no good since I wasn’t ever boiling.

Beta sells a lower temp thermal switch too now. It’s in the Beta aftermarket section somewhere. Fan goes off at a lower temp I guess. I don’t know how much lower than stock. Wait here..

https://shopbetamotorcycle.com/products/beta-4-stroke-lower-temp-thermoswitch?variant=13242944782389&currency=USD&utm_medium=product_sync&utm_source=google&utm_content=sag_organic&utm_campaign=sag_organic&utm_campaign=gs-2019-10-04&utm_source=google&utm_medium=smart_campaign&gclid=Cj0KCQjwyJn5BRDrARIsADZ9ykGv82QKSyFoEXPAGx4ICPksDC0UcX_4u0_9iuutKbA0KyanKWAiq7saAjQ-EALw_wcB

Edited by hawaiidirtrider

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On August 1, 2020 at 5:51 PM, LukeBrinkerhoff said:

Got the fan on and put some reflector tape on the tank. I didn’t quite buy enough, I feel like more of where the tank drops down needs covered than over the pump.

4E9CBEE2-B8CE-4BE6-A2FA-4A4E109C5C6A.jpeg

B778C0F7-167E-40A3-AFE8-8B9DF71B7E44.jpeg

More would be better but it's better than nothing.  Insulate the fuel line as well.  The Japaneese are not dummies. I got that FX in the tight switchbacks, lots of clutch, mud, 90+ degrees out, not a whimper, just the whir of the fan running.  

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