| Author |
Message |
    
Bartimus
| | Posted on Monday, September 01, 2008 - 01:26 pm: | 
|
A friend has an '04 blast with 7500 miles on it, that recently had the bottom end replaced (warranty).
Since it came back from the shop, it has far less power than it had before it went in, and it won't run worth beans in the mountains. It is leaking what the owner says is oil out of the airbox. It is out of warranty now, and I'm looking to try resolving this issue for my friend, but with no manual, and no experience with Blast's, this will be a bit of a challenge...
So far I've checked the timing and re-routed the oil breather to a catch can. But watching the carb with the air box cover off, I can see alot of gas vapor being blown out of the carb and into the air box.
If you rev it up, even more gas comes out and into the air box...
Shouldn't the intake be sucking this mixture INTO the engine instead of blowing it out into the airbox?
Also the slide in the carburator seems to have alot of side to side play as it moves up and down with the fuel demand.
Haven't had a chance to get back to it, and check the intake for leaks as that seems to be a common problem I'm seeing in the blast forum.
Anyone got any ideas?
Bart |
Ezblast
| | Posted on Monday, September 01, 2008 - 02:05 pm: |
|
A too tight primary for the majority of power loss, - the common reason - adjust by the sound method to the loose side - (I mentioned this next because a similar thing also happened else where could also be that cause - the cam is 1 degree or so off from where it should have been installed) Otherwise I would have suspected timing as well, but you said you checked that. Is the epa nozzle pointing away from the carb? Hope so.
EZ |
Bartimus
| | Posted on Monday, September 01, 2008 - 10:51 pm: |
|
EPA nozzle? What is that, and where is it located? should it be pointing out towards the airbox? |
Texas_firebolt
| | Posted on Tuesday, September 02, 2008 - 12:08 am: |
|
rings in upside down? |
Ezblast
| | Posted on Tuesday, September 02, 2008 - 11:06 pm: |
|
LOL - the nozzle is in the airbox in front of the carb throat - better your airbox a catch can than what that stuff will do to your motor in the long run. Loosen your primary till you hear noise, then tighten till noise disapears, lock down - adjustment done - enjoy your new found power.
EZ
EZ |
Bartimus
| | Posted on Wednesday, September 03, 2008 - 01:22 pm: |
|
EZ,
yea, that hose is gone now, routed to the catch can.
here is a pic, you have to really look close, but you can see the spray of fuel blowing OUT of the carb into the airbox when the throttle is opened:
The flash killed the view of the spray here, this is about 3/4 throttle.
I'm really concerned about this, none of my tubers do this, the XB seems to do a good job of sucking all the fuel mixture into the cylinder also.
what would cause this?
an intake valve sticking open?
why would pressure be coming FROM the cylinder?
The movement of the piston going down should be creating a vacuum and sucking the fuel mixture into the cylinder, not blowing it back out...
 |
Bartimus
| | Posted on Monday, September 08, 2008 - 02:50 pm: |
|
EZ,
I'm not sure how to adjust the primary on these blasts.
there is no inspection cover to view the chain, like on an XB, when you adjust the tightness...
How do you know if it is loose or tight?
Bart |
Seabass316
| | Posted on Monday, September 08, 2008 - 11:38 pm: |
|
To adjust the primary chain on the blast you have to break the lock nut loose on the primary adjuster( Thats that nut/bolt combo on the left bottom of your primary) undo the jam nut 3 turns, Tighten the adjuster bolt as tight as you can with 2 fingers,not with a wrench!( I know the book doesnt say that). Back off the bolt 3/4 of a turn,Hold the bolt then tighten the jam nut!There its adjusted! Also on a side note the factory sets all the primary chains the same. What they use is a "C" spacer.They believe that all the chains when new are the same(and I agree with that!) So they set them with this spacer. It should not be on your blast after the first service!Hope that helps! |
Bartimus
| | Posted on Friday, September 12, 2008 - 09:44 am: |
|
Thanks Seabass,
got that done, the blast still seems like its having power issues, i'm thinking it's carburation as I feel some surging, it also spits back through the carb often.
I also have a question: What is the electronic device bolted to the butterfly on the carb? is this a TPS? If so, why would a carbed bike have one?
Bart |
Wyckedflesh
| | Posted on Saturday, September 20, 2008 - 11:15 pm: |
|
You heard my thoughts Bart. I still think its a valve issue, but I hadn't thought about the intake cam being off. Makes sense. If the intake valve is open as piston is rising, then its going to push the air and fuel back out the carb. Makes even more sense that it started when they got the bike back after the bottom end rebuild. Might be time to buy a hot cam, some head work and maybe a big bore kit  |
Bartimus
| | Posted on Tuesday, October 07, 2008 - 11:20 am: |
|
EZ,
Your diagnosis was correct! Upon closer inspection I found the exhaust valve off by one tooth:
Real nice work that shop does! LOL
I readjusted the cams, and then re-checked the timing. Here's what it all looked like when I buttoned it up:
The little sucker has some grunt now!
Thanks again everyone for your help and suggestions!
Bart |
Jeannievb
| | Posted on Saturday, February 21, 2009 - 11:33 pm: |
|
Can i ask a question here?
I if the cams are off by a tooth or two, will it cause the top of the head sound like it's tapping.
Here is the back story.
I put the new rocker box gasket on 02 buell blast. buttoned everything up. for unknown reason i removed gearcase cover and cams came out with it. (crap) I removed head cover and rocker box, down to the gasket. pulled push rods out, lifted hydraulic cam followers with finger and replaced cams (i thought correct timing and still sure that it was right). dropped in push rods and replaced gasket and lower rocker box and head cover.
started bike up and now i hear tapping coming from head right around where exhaust bolts on.
What is the reason for this and did i ruin something?
please help |
|
Troubleshooting (Poor Starting/Running/Handling/Ride Issues) »
Archive through April 15, 2009 »
Blast, loss of top end power, unable to pull 70 MPH