Hey everyone...

Pretty new to F4i problems... I've been searching around trying to diagnose my issue... but I just want further confirmation from anyone who may have had the problem as well.

I have read the the Fuel Pressure Regulator is a common issue in these bikes, but I'm not sure if my symptoms fit exactly.

Off the line I can feel the bike lunges from what feels like misfires. It lasts until I get into 3rd or 4th before the bike calms down.

Thinking that it could be the FPR, I pulled the tank and just visually looked at it while manually adjusting my CCT. It certainly doesn't look new... (bought the bike used last year). So it's a candidate for replacement.

However if it was the FPR, would it matter if the bike was under load or not? I mean I can let it sit in Neutral, and rev the engine (climbing the RPMs as if I were riding it) and I hear absolutely NO misfiring at all. It's only when I put it in gear and take off. And it's a fairly consistent jolt... slightly faster than once per second... when I start off, and then quicker (but less of a jolt) as the RPMs increase before it settles down to nothing.

This makes me think it could be something more like an injector or plug that's faulty since it feels like it's hitting at a pretty consistent interval.

Also I've noticed that if I'm cruising at highway speeds, if I hit a bump in the road I can feel it doing the same thing, but the jolts aren't strong, and when I back of the gas a little it evens back out, and I can climb the RPMs again.

I'm going to find a wire so that I can jump the pins and get a reading from the flashing FI light. I just want any input I can get right now. This is my daily rider, and ALL that I have...so I have to keep it on the road.

Thanks in advance for any help, and I apologize to any of the regulars if this is a common question answered millions of times already. I just haven't found any threads in the forums explain the exact problems I have for me to go start buying and replacing parts.

 

have you done your general maintenance ??? change the oil and filter, plugs and airfilter??

when you say a jolt does it feel like knocking in the block ???is it audible or just felt??? i am at the understanding you just feel it.

personally i would change the oil check for brass colored shaving and do the spark plugs go with iridiums no matter what. clean or change the air filter.
run some injector cleaner through it...

see if that changes anything if not it's pretty much official you will be checking other compnents

good luck

 

How old are the spark plugs? Could also be a stiff link in the chain.

 

The jolting is accompanied by a sound... but I don't know that I'd call it a knocking sound... more of a quick loss of power sound. Feels/Sounds like something is making the engine drag while I'm accelerating.

I hadn't thought about a stiff link in the chain, thank you for the input.

I need a new rear sprocket because I rode all winter, and even though I kept my chain lubed, and clean, some of the teeth have gone missing. I know the chain isn't skipping or anything... but certainly not a great way to ride.

As far as the maintenance... I've cleaned the air filter... changed the oil... the only thing I haven't done is change the plugs. So I know they could be the culprit as well. I just find it weird that the problem only happens when under load... if it were plugs, I would think it'd do it in neutral as well. Just trying to really pinpoint before I start throwing money at it... kinda strapped for the next few weeks...so I have to spend wisely to fix my baby.

 

So I took my bike out for a spin around the parking lot at work with my helmet off, and sure enough I can hear the problem better.

Turns out it's my chain slipping. I could hear it clack as I put it under load. The few teeth missing, has turned quite rapidly into many teeth missing or have the tops chipped off on the driven sprocket.

Just ordered a sprocket kit from my local bike shop. Hopefully I'll be able to report back with an update that it's fixed next week when the front and rear sprockets come in.

 

good deal awesome you solved the issue