Posted this in the Engine/Fuel/Exhaust forum but not much traffic over there,. Hope I can get an answer or two here! So heres the scoop:

Hey guys. Hope someone can help me out. I recently bought an 08 Street Bob a few weeks ago. I've noticed that when I'm in first, second and third gear at a steady speed, the bike kinda surges back and forth. I just installed a PC-V today hoping it would correct it but there was no change. Could the belt need tightening? Dyno tune? Problems with the primary gear? Tranny? any help would be appreciated. Hope to get it taken care of instead of taking it to the dealership for answers. Thanks -Shaun

 

May be a dumb question but when you installed the PC V did you put a new map on it?

 

This is a HIGHLY uneducated guess but what I have seen.

Check your battery connections. Reason being is there may be some electronic connection problem to make it pull back then surge if loose. If its not getting full battery useage this could cause a problem.

Dirty Gas or dirt in tank or filter?

Personally I would look at the electrical idea from what I have experienced.

Now those that know more than me please chim in.

 

I got the PC-V from FuelMoto and it came pre-mapped.

Tank has had 3 new tanks of 93 octane since i've had it. Also checked, cleaned, and retightened battery connections. All is good on the electrical side from what i see.

FYI - I have V&H Big Radius Exhaust and what looks to be a SE high flow air intake under the "football" cover. Anyway to be sure its a stage one intake?

 

Did some research on the topic of surge and reasons below...

1) Jets/EFI are dirty .... put some cleaner in it
2) Your running to Lean
3) All parts of your air cleaner not installed or properly installed
4) Some say it could be your sprocket or belt could be bad
5) Could be a computer problem
6) Bad Spark Plugs

Thats all I could find but I know theres more. The above are common problems that cause surge.

 

Thanks for the above and beyond work csbreeze! I'll change the plugs tomorrow and see what they look like. Will also do a run through on the air cleaner. Don't really want to throw money at it guessing, thats an awful lot of variables! guess i'll ride to the local dealership and see what they say if i don't find anything tomorrow. thanks again!

 

Also, just remembered comming across a thread about some bikes having #8 injectors that were crap and people went to #25 injectors to fix the problem?. couldnt find the thread again, does my bike have these #8 injectors??

 

If my memory serves me correctly that problem was with 2006 models. People had surges with the injector problem. I do not know for sure what injectors you have but I would bet money you dont have the defective ones because there was a recall on them. No notices were sent out but dealers fixed them for free.

I would hunt for another wrench than HD if possible in your area. HD will rape you messing around with your bike to not find anything. My experience the best mechanics no longer work for HD dealer.

 

My 10 Dyna Super Glide surges, my son 06 Street Bob surges. It seems that in first to third it is normal.

Just don't ride in that range long. It accelerates through those gears at wot without any surges.

 

It is not normal. Might be common, but not normal. My 2010 Street Bob did it in 1st and 3rd.
I have a SEPST, and after adjusting the VE Tables, and doing some Smart Tunes. I have eliminated the the surge completely. Cruising in any gear is smooth sailing. You're running lean is my guess.