Brute wont go more than 35 mph?!?!

HammeredFlat4 · May 4th, 2010, 11:48 PM

Hey guys I am having a problem with my 07' 750i. It sat for a few months in the garage and then when I tried to start it up for the first time it would crank and crank but it wouldn't fire. I got it running with some starting fluid and it started to run but its still not right, it pops out of the exhaust at low rpms and just feels like it has no power and it will not go any faster than 35 mph. I have checked all the easy stuff, carb/airbox boots look good, exhaust is tight and looks good, ran it without the gas cap, and I even changed the plugs. Any ideas what the problem could be? Fuel pump, clogged jet, valves out of adjustment? It has 28 hours and a little over 200 miles on it. Any help is appreciated.

NMKAWIERIDER · May 5th, 2010, 12:25 AM

Quote:

Originally Posted by HammeredFlat4

Hey guys I am having a problem with my 07' 750i. It sat for a few months in the garage and then when I tried to start it up for the first time it would crank and crank but it wouldn't fire. I got it running with some starting fluid and it started to run but its still not right, it pops out of the exhaust at low rpms and just feels like it has no power and it will not go any faster than 35 mph. I have checked all the easy stuff, carb/airbox boots look good, exhaust is tight and looks good, ran it without the gas cap, and I even changed the plugs. Any ideas what the problem could be? Fuel pump, clogged jet, valves out of adjustment? It has 28 hours and a little over 200 miles on it. Any help is appreciated.

If you didn't drain the carb bowls prior to letting it sit those months, the gas has dryed and left a varnish plugging the jets and passageways. Asside from a full Vatt & rebuild of the carbs, you need to soak them in something that will desolve the varnish. Gas won't do it. Spray carb cleaner will, but hot have to full the bowls with it by spraying it up the overflow tubes...about a half can each after draining the gas out. Then pull the air cleaner and cage out as well as the fire screen. With your finger lift each slide (CV) and spray doen the main asperator. Then have someone hole the throttle open and with the tube on, spray into every port you can see with a flash light after the butterfly. Dont try and start it for 24 hours...let it sit and work. Do the spray down the intake side a few times. The next day, pull the seat and the ECU. Under it you will se the fuel control valve, turn it to PRI. Put the choke on and start it taking the choak off as soon as it starts. After it runs a few seconds turn the calve back to the ON or run position. It will runn bad and smell worse while burning off the carb cleaner. Put some carb cleaner in the gas tank too

YOU did drain all the old gas out of the tank and put fresh in...right? That's rule #1. If not, do that first.

HammeredFlat4 · May 5th, 2010, 12:45 AM

Quote:

Originally Posted by NMKAWIERIDER

If you didn't drain the carb bowls prior to letting it sit those months, the gas has dryed and left a varnish plugging the jets and passageways. Asside from a full Vatt & rebuild of the carbs, you need to soak them in something that will desolve the varnish. Gas won't do it. Spray carb cleaner will, but hot have to full the bowls with it by spraying it up the overflow tubes...about a half can each after draining the gas out. Then pull the air cleaner and cage out as well as the fire screen. With your finger lift each slide (CV) and spray doen the main asperator. Then have someone hole the throttle open and with the tube on, spray into every port you can see with a flash light after the butterfly. Dont try and start it for 24 hours...let it sit and work. Do the spray down the intake side a few times. The next day, pull the seat and the ECU. Under it you will se the fuel control valve, turn it to PRI. Put the choke on and start it taking the choak off as soon as it starts. After it runs a few seconds turn the calve back to the ON or run position. It will runn bad and smell worse while burning off the carb cleaner. Put some carb cleaner in the gas tank too

YOU did drain all the old gas out of the tank and put fresh in...right? That's rule #1. If not, do that first.

Ok thats what I was thinking too. I did drain the old gas and put fresh gas in the tank. I think I will just remove the carbs and rebuild them that way I know they are clean. Do these things have fuel pumps? I thought only the efi models had them but it shows a fuel pump in the 07's parts diagram, anybody have problems with these?

bustamove · May 5th, 2010, 02:06 AM

yeah any carbed bike needs a fuel pump when the gas tank is lower then the carbs.. on dirt bikes and some snowmobiles the tank is higher then the carbs.. its not a high PSI pump though

gusmx5 · May 5th, 2010, 05:21 AM

I would say it is the fuel pump for sure...mine did the same...put it in neutral and push the throttle all the way and see is it revs up or after some revs it backfires.If it does this then take out the fuel pump and clean it.Been there.....

NMKAWIERIDER · May 5th, 2010, 09:50 AM

The carbed bikes have a "Pulse" type fuen punp just after the valve I was talking about. Vacuum lines fron each intake send a pulse to each side of the diaphram and pump gas. If the check valves in the pump are not sealing, it will have low or no fuel delivery..of course if the diaphram is cracked.. same thing. The PRI setting on the valve helps get all the air our of the system but don't leave it there.

The vatting is the most important part of the carb rebuilding. If you dont have a carb vatt, then take them to a shop that does. Remember to completely dissassemble them first. Leave no plastic or rubber parts in.