Hi, I am in the UK.  I recently bought a 2005 Suzuki S40 650 - an American import, form Georgia (GA) I believe.  Just over 9000 miles on the clock. Suzuki S40/Savages are unobtainable in the UK - have been for some years.   I had to send it back to the dealer twice for attention - very bad backfiring and very loud silencer.

The dealr rebuilt the top of the cylinder (so they say!) The bike runs okay once it’s well warmed up, but stutters and misfires when first started up, unless at least half choke kept on for first 5 miles, then it smooths out. If you push in the choke fully too soon, it misfires and sputters.

The dealer say they did the followin work on it:

Brand new cam chain tensioner – one of the later, better ones;
Cylinder head has been rebuilt with two new exhaust guides – genuine Suzuki ones, the cylinder head was sent away to a specialist, head warmed up , old ones pressed out and and new ones pressed in;
When they stripped down the bike this time, they noticed it was damp around one of the guides on the exhaust side, so replaced both exhaust guides;
Genuine new head gasket;
Yamaha exhaust to replace the old one which was causing the bike to backfire and was very loud, as the previous owner in the U.S. had removed the baffles;
New cylinder rings
New rubber plug on cylinder head

What I am asking is this: is this sort of problem on firsst start up and for first 5 miles common?  Is there any way to cure it?

I hate to say it Kate, but I think your mechanic is either incompetent or soaking you for cash.

Your problems sound like jetting that is too lean - that's all. Please tell me that the backfiring wasn't the reason for the head rebuild?

Thanks for the replies from Gary and Eegore, which were helpful.  No, the poor running on start up and for first five miles or so is not just because the engine is cold.  I have been riding bikes since the early 1970s, and plenty of bikes with carburettors and chokes, so know how a bike should run and when it's not quite right.

Yes, the problem is almost certainly running too lean and a re-jetting is needed, and I am taking it into a really fantastic bike mechanic locally on 16th September who is going to look at re-jetting it.

Yes, the original problem for which it went back to the dealer twice was very serious bad-firing and silencer that was too loud because the previous U.S. owner had taken the baffles out.

I did not pay the dealer anything extra for when it went back to them and they picked it up for free (twice) and took it back to the other side of the Pennines (and in fact it's still under their 3 month warranty). They DID rebuild the cylinder head and replace the exhaust valve liners, etc., as described.  They've tried twice to sort it out, and so there is not much point in sending back to them again, so I'm trying my local bloke for the re-jetting.  

Meanwhil I am buying a brand new Royal Enfield Meteor - had a test ride on one - they are terrific bikes, refined 2021 engineering.  

Thanks for your help, guys.

GothicKate wrote on 08/31/21 at 05:33:56:
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Yes, this is completely normal.

My bike takes a good 7-8 miles of riding with the enrichment knob pulled halfway out.  This is normal and it's the exactly the reason they put an enrichment/choke on the carburetor.  

You are at or neatr the begining of the UK autumn, you certainly shouldn't need five miles of full enrichment/choke at that time of the year. In mild by US/UK standard NZ winters I use two or three miles of enrichment/choke. Upon starting the bike I generally push the button halfway in, have you tried this method. I note you had a new rubber plug in the cylinder head. It may pay you to investigate the Verslagen aluminium and O ring version. Some are saying the mechanic ripped you off, maybe, but when they see oil on the block, they will tend to make assumptions about head gaskets. check the technical info on this site for jetting issues. My bike is pretty bog stock and I've had 94000 plus kms 58000 miles without serious issues.

+1 for Gary !
Cheers!