New to the forum and was hoping someone more familar with these could help..
I have a customer who brought in his 04 bruin after he attempted to rebuild his carb on his own.. half the new parts went in, half he brought to me in a bag.. The quad had been sitting for about years prior to him doing all this. The issue is that it idles great but bogs out after 1/4 throttle. Carb looked new inside and out but I still removed and rebuild to be safe. (this included ultrasonic cleaning and compressed air for everything. All jets replaced with new. Re-installed, same issue. But it will rev up no problem when I cover the snorkel intake to the airbox.
It’s obviously starving for gas or way too lean with air. While I’m very comfortable with older and 2 stroke carbs, this one was different than others I’ve worked on with the vaccuum controlled slide etc.
Upon initial inspection, I noticed an extra jet Im not used to seeing, which I guess is a "starter jet". The diagram isn’t clear but what I found in there was a 127 jet. On the higher pedestal in which the slide needle goes into, I found a 57.5 jet. On any other carb I’ve worked on this is the main jet, so it looked to me liked the owner may have confused the 2 and put the smaller jet in the main so I swapped them and reinstalled. After doing this, it would not start or idle without a lot of throttle and would immediately die without throttle. (I did this without the airbox installed, but noticed it looks like the pulse line from the head pressurizes the carb through the airbox – another first for me). It was running pig-rich also, strong gas fumes, very wet plug after only a minute or so..
My next step is to try this orientation with the airbox in and sede if that makes a difference.
Other things I’ve tried – new gas (plenty of flow from petcock), new plug, inspected intake boot (looks new), sprayed starting fluid all around looking for air leaks.
The mixture screw is blocked off so I haven’t touched that. It’s worth noting that the machine looks brand new and was well maintained until sitting and was always stored inside.
Any other ideas?? I’ll update with what happens after putting the airbox back in and trying again. As of now, with the jets the way he had them, it will only rev up with the airbox inlet about 75% covered and under any circumstances, it WILL NOT run with the choke on – even halfway engaged, it cuts right out..
Any help is appreciated!! :peace:
Tried running
