Engine Upgrade problems 2007 Honda Shadow Spirit
Posted on 2009-05-15
I have a 2007 Honda Shadow Spirit. The specific model is the VT750DC.
Recently I installed:
Cobra Streetrod Slashdown Exhaust for Spirit 750 DC (Chain Drive)
Cobra Jet Kit - Honda Shadow Spirit 750 DC (Chain Drive) - Stage 1
Runs great and I'm running with NO baffles. I used the DJ106 and DJ104 jets from the stage 1 kit. Now comes the problem, I also ordered and attempted to install:
Thunder Manufacturing Round Custom Air Kit
Basically it's an open round K&N air filter smashed between two chrome plates. It gets LOTS of air flow. The air filter kit came with a DJ134 and DJ138 main jets which I replaced from the DJ104/106 jets that came in the kit.
Some things to note, there is no Stage 3 kit for my bike. BUT, the air intake is made specifically for my bike. It also says that a jet kit (not included) must be installed. So I'll ASSUME that the stage 1 fuel needles and springs are OK but that is probably where my problem lies. I don't know where to adjust the air/fuel mixture screw to because I'm NOT a carb man. I'm just following what instructions I have and they are currently set to 3 1/2 turns out which is what the cobra kit said to do.
Here's what happens and doesn't happen.
Accelerates smooth under low throttle on flat (down my street to the main road).
The road I am testing on is completely flat.
When I "get on it" it stutters for a second but then really takes off.
When I let off to shift, the RPMs drop, but as soon as I get on it in 2nd again it stutters for a second. This repeats all the way through fourth.
So I turn around and head to my house (up a hill) and it won't climb the hill unless I downshift to 2nd and get the RPMs and throttle up. Normally I climb the hill in 4th. Once on my street, it putts along as always because there's little demand on the engine. I also tried restricting air flow by taping off the front 1/2 of the filter and it didn't make it any better. I REALLY think I'm getting too much air.
If I put the stock air box and the stage 1 jets on, it works fine.
Here's what I am capable of doing, looking for guidance on WHAT to do.
put baffles in exhaust
adjust air/fuel ratio (?? in, out ??)
you tell me
here's what I can't do (without ordering parts)
swap out the springs or needles
swap out the jets (i don't have any bigger jets than what the air filter came with).
Let's have at it. I'd like to solve this myself without taking it to the honda shop.