Just bought 2008vfra seems to have flat spot/hesitation in 1st around 5 and 7 rpm?

Hi All

I have a new to me 2008vfr (abs) that i am loving. It was a two owner bike before me, the last owner having it for two years and only puttting 450 miles on it. I have already tied her (yes her) miles in the first month =). Anyways still getting used to this bike and I have noticed that in 1st year I have some strange flat spot/hesitation if I take the rpms up to say 9k. Besides the vtech cutover point there are two other spots that seem to drop out on me. I thought at first I was just ham fisting the throttle but its almost everytime. This is actually my first FI bike. Does this bike have a known issue, anything I should be looking for? I live by the coast in florida so I run 91 ethonal free gas which seems to help just alittle. Was going to dump a can of seafoam in? Really not sure if its the injectors but feel like on my old carbed bikes when something was wrong with the jetting or needle.

Thanks again! Ill try to post pics of the bike soon.

 

I had a 2007 and the only flat spot I really remember was right before the VTEC would engage. I was routinely above 11,000 rpm and don't remember anything after the VTEC being flat.

Unfortunately I cannot tell you if there is an issue, I can only say that it doesn't sound like my experience. I only had that bike for 4 months, so I would get some input from some of the guys who know the 6th gens inside & out.

 

Thanks! I have been reading up and it maybe the PAIR valve O2 sensor hesitation. I have noticed that my bike hates being under really 4k rpms...Just getting confused on what is the proper fix, block, blocking plate, o2 sensor removal, some airbox hose plug, etc......

Coming from a 75 yamaha XS650 theres alot going on here. =)

 

If the previous owner of the bike has only done 450 miles in two years, it is possible that they owner did not bother to service the bike in that time. If you have no idea when the bike was last given a service then I would get that done first, and see if the issue is resolved.


SkiMad

 

There is a known off idle stumble if you're careless with the throttle as the afore mentioned pre VTEC flat spot. Sounds like it just needs some attention. If the bike has been sitting (especially outside) I would check the airbox first to see if it was turned into a squirl storage facility. You'd be surprised how much air starvation robs you of power...

 

Any by the way, IMO, all of these V4s hate being under 4000 RPM.

 

Good news is the bike only has 8400 miles on it. So I changed the oil to amsoil. checked the coolant, cleaned and lubed the chain. I will pull the tank and check the filter this week. It was stored inside a garage. Was in good shape I can just tell the chick never rode it. I drove it home 70miles when I purchased it and it ran totally fine. I just noticed the other day if I acelrate hard in 1st I hit two flat spots. I have noticed the throttle to be alittle abrupt too, but I thought that was more my riding skill than anything else.....

Best,
Justin

 

First fill HER up and put some seafoam to clean out any build up in the injectors......easy and cheap fix. Hopefully you see a diff
+1 on what everyone said also...air box, you would be surprised of some of the pictures of critters building a nice little nest. Good luck

 

Got to thinking - have you checked the chain tension over the entire chain? I know you said you cleaned and lubed it, and maybe this is way out there, but could a significant tight spot on the chain be giving you that feeling? Obviously its a 10 second diagnosis and costs nothing, so can't hurt to check.

And garages don't stop them critters like mice moving up into the air box. To the contrary, dem little fur bearnin varmints come in outta the cold. I used to surround my bike (in the garage) with about 4-6 traps. Make them little fuckers walk the peanut butter gauntlet before they take up residence in my steed!

 

concerning the chain, I havent.... I found a pdf of the manual online but do you remember the play? When cleaning with the grunge brush nothing jumped out at me...

 

Here ya go bud

 

niiiiice.

 

Especially so in higher gears than first. :smug:

 

Never know what you can find in an air box...

https://bstassen.files.wordpress.com/2014/10/img_4831_resized.jpg
http://gl1800riders.com/forums/attachment.php?attachmentid=73595&d=1355177867

I'm just sayin'...

Plus 1 on what duccmann said about clogged injectors also.

As for the abrupt throttle response; it's an acquired taste! Some say you must eliminate it by throwing tons of money at it with a power commander, O2 eliminators, PAIR block offs and such. I say ride the bike a few months in different conditions and then decide which modifications you want to make. A lot of "issues" will disappear once you get familiar with the bike.

 

It's possible that varnish developed somewhere in the fuel system and the detergents dissolved/broke some free. Run some Seafoam ad then if that doesn't clear it up, then consider getting your injectors professionally cleaned. I don;t know how long the bike sat, but obviously quite a while with that low of mileage on it. Give the injectors a real good clean. It does wonders!

 

thanks all! Ill dump a bottle of seafoam in and hope for the best. Im hoping ill just get used to the throttle response, like all things. Any car or bike I have owned takes some adjustment period.

The dead spot is a strange one (at least coming from my last few bikes). If I take off from 1st up to 10k rpm, no matter how steady I try to hold the throttle it just cuts out and is not very smooth. My other gears dont seem to have the same problem.

One other related note, I find that I like to cruise around 6k due to the down low bogging, which happens to be when the VTEC is supposed to kick in, any harm riding steady right at the 2 to 4 valve cuto off? In my head I keep imaging the valves continually changing back and forth...definitely something I never worried about on my non vtech bikes? Sorry I even be worry about such a thing?

 

I've just been reading some screaming rave reviews of Red Line 60103-12PK Complete SI-1 Fuel System Cleaner. 195 four star plus reviews on it, nearly all saying the same thing. Personally, I have never tried it, but I have used a full bottle of SeaFoam in my other bike and I did not really see much difference. I'm game to try the Red Line stuff. It's supposed to have the strongest concentration of the stuff that actually cleans injectors. Read here: http://www.amazon.com/Red-Line-60103-12PK-Complete-Cleaner/dp/B000T9RLT0/ref=cm_cr_pr_product_top

Oh, and to back up my comment regarding the SeaFoam, the vibration issue I had was caused by fouled injectors as was the erratic idle and off throttle behavior because when I changed the injectors, it all went away, so the SeaFoam didn't touch the problem. I don't know if Redline would have or not tho. I'll probably order some Friday.

 

PC5 and custom dyno tune did wonders for my '04 - whole new bike