Got A New Exhaust Fitted - Looks Good, But...

[Jim's_a_Thai_Fox]

Hi,

I got back my VFR400 yesterday (after a 3+ month wait, but that's another thread). It's got a nice new paint job.

I also asked for a new exhaust as the 'mumbles' (is that right? - the inner pipe inside the previous end-can became dislodged and there was loads of misfiring, spluttering etc.).

So, I got a nice looking carbon exhaust fitted. Looks fab.

Took out for a maiden run today... and it's crap!

What I mean is there is a serious reduction in torque - accelerating from 3-4k revs before was fine, in any gear. Today, I had to have it in the range of 8k+. Also, there is NO acceleration in top gear (6). Previously, there was plenty of grunt. Finally, to cap it off, I open the wrist to the limit and it won't get past 150 kph... Again, with the previous exhaust, it would it the red line in 5th and 6th with no problem. I had the speed re stricter taken out a few years ago.

Is this problem simply down to the exhaust being of an inferior quality? Just revving it in neutral, there doesn't seem the response of old, a bit sluggish firing in the lower range (sparks, maybe?). I know it isn't a balanced cam in-line 4 and will never be ultra responsive like a CBR, but still, this isn't really on.

Now, before you say it, I will go back to the Thai mechanic. But, from his point of view, he's stuck on a new can as requested, and if it's not as good as the old one, well, tough titty mate.

I paid an extra 7k Baht for some new valves and sparks and to give it a service. The result is a machine that feels as though it has seriously reduced output.

Any help/advice as to why my beloved steed is now longer the beast it was, is appreciated.

Cheers

James

PS if you want to buy it, I'm selling for 60k. Has CM plates and book. PM me and I'll send you a photo. Despite the above niggle, it's still a top machine!

[solent01]

Jim, was it just the end can thats been replaced or the whole system? Does the bike have any other mods? (air filter-jets)

[goldfish]

You let a thai mechanic replace the valves? I'm sorry, but lord knows what he's been up to in there. The valves probably don't seal, the cams been replaced with a worn out spare and he couldn't remember where the oil feed went. Suspect the exhaust is the least of your problems

[tuktukmike]

Got to agree with goldfish on this one.

If you have had the valves replaced i doubt that the new ones were ground in, thus losing compression.

Also are you sure that the valve timing is not now out, this happened to my yammy as the engineer (ha) never marked the timing chain position.

Not sure it is a good time to advertise after what you have told us.

Mike.

[LivinLOS]

As others have said.. If you have let someone do an upper head job then diagnosing it as a end can problem is a leap of faith at best..

I was hyper awkward about who I would let on my CBR.. Not only the lack of skill, but the fact that being a farang I assume he would feel he could cut corners, use parts I wouldnt agree with, etc etc etc etc..

Time to find an expert to repair the repair..

[Jim's_a_Thai_Fox]

Hi,

cheers for the posts. In the previous post i was referring to the 'baffles' inside the end can, and not the 'mumbles'...!

Anyhow, given the advice I've been given, I'll take it to Red Baron for them to have a look over.

On that note, any recommendations on where is best to get the VFR checked over?

Cheers

James

[Awk]

Hi,

cheers for the posts. In the previous post i was referring to the 'baffles' inside the end can, and not the 'mumbles'...!

Anyhow, given the advice I've been given, I'll take it to Red Baron for them to have a look over.

On that note, any recommendations on where is best to get the VFR checked over?

Cheers

James

There's english speaking thai meachanic working in a shop

not far from the old 700 centre here in CM.

I've visited him a couple of times in the process of checking out used vfrs before buying,

and he seems firendly and competent, and not out to rip you off.

Not sure what the address, so probably easier if you call him yourself for directions.

His name is Nut (of course), and the number is 08 1952 4433.

[Gary A]

Let us know what you find out. I seriously doubt that it's the muffler. I'd guess that it is out of time, either the ignition or the valve train.

[Jim's_a_Thai_Fox]

The reason I mentioned the end-can was simply due the previous exhaust's end can getting rusted inside and the baffles went. The subsequent result in spluttering, misfiring etc. seems to be very similar to the bike now...

...I didn't ask him to replace any valves, but there was a clicking sound as they had been 'shimmed' (?) by my old mechanic. This sound had now gone, but the power output and low/mid rev torque + top speed has also gone.

As for Awk in Cm, many thanks, but Changers is a little far. If I have no joy finding a good one down here, I can always give him a call... but it's tricky diagnosing problems over the phone.

Cheers for your continued input,

James