SuzukiSavage.com - Backfire issues..

bikergirluk

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Backfire issues..
09/26/10 at 07:54:49

Hi all...after dropping a valve and having to replace my very mashed up engine with a 2nd hand one...the bike is up and running again...However, the backfiring is so ridiculously loud even at the slightest decelerration, that a woman carrying a small baby nearly dropped it!!!

I noticed that one of the studs holding the exhaust pipe to the engine has parted company with the bike in the 40 or so miles I have done so far...I guess this means the seal isn't real good...also there is no gasket, but there wasn't on the old engine......

I had to put this engine back together as the top end was off when I got it...did put new cam chain and tensioner on...Noticed when I replaced decompressor cable as the old one snapped on the screw thread, that when I got it to TDC, on here it says both sets of rocker arms should have free play...only the set nearest the rear of the bike had freeplay, no matter how many times I turned the crank and checked, using a straw in the spark plug hole as per these forums!!

So...do you think its a valve adjustment issue, or not a tight enough exhaust issue, or do I have to go messin with the carb and do the spacer mod??? Or maybe rejet it?? I have an aftermarket muffler (tailpipe for us brits) and standard header pipe...Don't know what make the muffler is, it was on there when I bought it...

Before I replaced the engine, there was a fair bit of backfiring...more so after I had the cam chain and tensioner done...but this is beyond a joke. Getting flames too, yellow and sometimes blue outta the end of the muffler. Don't wanna carry on riding it until I know how much damage I may be doing....

Undecided

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bill67 Serious Thumper Offline old tired Posts: 8517 genoa city wisconsin Gender:	Re: Backfire issues.. Reply #1 - 09/26/10 at 08:12:15 First you need to get the exhaust fixed then if the jets are stock you need to go richer.
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bikergirluk YaBB Newbies Offline SuzukiSavage.com Rocks! Posts: 46 bristol UK Gender:	Re: Backfire issues.. Reply #2 - 09/26/10 at 08:12:25
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bikergirluk YaBB Newbies Offline SuzukiSavage.com Rocks! Posts: 46 bristol UK Gender:	Re: Backfire issues.. Reply #3 - 09/26/10 at 08:12:55 Hopefully one of you guys may now what sorta tailpipe/muffler this is?????
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bikergirluk YaBB Newbies Offline SuzukiSavage.com Rocks! Posts: 46 bristol UK Gender:	Re: Backfire issues.. Reply #4 - 09/26/10 at 08:14:55 Thanks Bill, I ghave saved a lot of info on how to do that...first things first tho, new exhaust stud to see if this helps...D'you think I also need to get a gasket???
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verslagen1

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Re: Backfire issues..
Reply #5 - 09/26/10 at 08:46:34

bikergirluk wrote on 09/26/10 at 07:54:49:

I noticed that one of the studs holding the exhaust pipe to the engine has parted company with the bike in the 40 or so miles I have done so far...I guess this means the seal isn't real good...also there is no gasket, but there wasn't on the old engine......

1st step of backfire reduction, remove air leaks from the exhaust system. The seal is several layers of soft metal. so on the old engine it may not look like it's there cause it smashed. Someone said that copper wire wrapped around the header will prevent bluing, so this might be a stop gap, take some copper wire, form a circle, twist them together so they won't separate, hammer flat and use that for you gasket, never done this, but if you don't have one...

bikergirluk wrote on 09/26/10 at 07:54:49:

... when I got it to TDC, on here it says both sets of rocker arms should have free play...only the set nearest the rear of the bike had freeplay, no matter how many times I turned the crank and checked, using a straw in the spark plug hole as per these forums!!

Now I have to ask since it's common mistake... You turned the crank CCW, same way the wheels rotate forward? And you watched for the intake valve to open and close then set it on the following TDC?

bikergirluk wrote on 09/26/10 at 07:54:49:

So...do you think its a valve adjustment issue, or not a tight enough exhaust issue, or do I have to go messin with the carb and do the spacer mod??? Or maybe rejet it?? I have an aftermarket muffler (tailpipe for us brits) and standard header pipe...Don't know what make the muffler is, it was on there when I bought it...

An open 'tailpipe' will always have more of an issue with backfiring than the stock pipe. You'll have to eliminate all of the probable causes and get it tuned just right. work out the mechanical issues 1st. Then clean the carb, then adjustment. If it won't adjust to solve the problem then rejet. You might get a look at your jets and let us know what size they are. You might have a different set of number due to being metric but our number are for the main jet would be from 145 (stock) to 165 (rich). A 'tailpipe' like yours will need a rich jet.

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bikergirluk YaBB Newbies Offline SuzukiSavage.com Rocks! Posts: 46 bristol UK Gender:	Re: Backfire issues.. Reply #6 - 09/26/10 at 14:15:00 Ah Mr Verslagen...you are a true mine of information...if it wasn't for your posts, the bike would still be no better than a paperweight in the garage...thanks dude
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bikergirluk

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Re: Backfire issues..
Reply #7 - 09/26/10 at 14:17:00

Now I have to ask since it's common mistake... You turned the crank CCW, same way the wheels rotate forward? And you watched for the intake valve to open and close then set it on the following TDC?

I turned it ccw...read so many postings telling me to do that, and watched the straw in the spark plug until it was at its highest point....which one is the intake valve...front or rear when engine in the frame???

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bikergirluk YaBB Newbies Offline SuzukiSavage.com Rocks! Posts: 46 bristol UK Gender:	Re: Backfire issues.. Reply #8 - 09/26/10 at 14:20:45 btw...which type of carb do we have..Mikuni or Keihin or something else..Verslagen is are the sizes you gave me for main jet or pilot jet??
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Charon Serious Thumper Offline Posts: 1811 Harvard, NE Gender:	Re: Backfire issues.. Reply #9 - 09/26/10 at 15:25:18 The intake valves are on the rear of the head, nearest the carburettor. The exhaust valves are on the front of the head, nearest the exhaust pipe.
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verslagen1 YaBB Moderator ModSquad Offline Where there's a will, I want to be in it. Posts: 28886 L.A. California Gender:	Re: Backfire issues.. Reply #10 - 09/26/10 at 15:34:12 bikergirluk wrote on 09/26/10 at 14:20:45: btw...which type of carb do we have..Mikuni or Keihin or something else..Verslagen is are the sizes you gave me for main jet or pilot jet?? Mikuni BS40 For our main jet pilot is 50 or 55 (don't pay much attention to this one, never had any trouble with it)
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DrunkenDwarf Senior Member Offline Morning Zombie Posts: 325 Seattle, WA Gender:	Re: Backfire issues.. Reply #11 - 09/26/10 at 16:55:52 verslagen1 wrote on 09/26/10 at 15:34:12: Mikuni BS40 For our main jet pilot is 50 or 55 (don't pay much attention to this one, never had any trouble with it) Stock pilot is 52.5 without bleed holes on a 2007. Not sure about older models. -D. Dwarf
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bikergirluk YaBB Newbies Offline SuzukiSavage.com Rocks! Posts: 46 bristol UK Gender:	Re: Backfire issues.. Reply #12 - 09/26/10 at 17:42:02 145 (stock) to 165 (rich). I found this ebay ad: If I ordered the one numbered 160 would that be close enough??? http://cgi.ebay.co.uk/MIKUNI-MAIN-JET-BRASS-ALL-SIZES-AVAILABLE-110-400-/1105...
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verslagen1

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Re: Backfire issues..
Reply #13 - 09/26/10 at 17:56:09

Get a range of sizes, and I'd hesitate to buy those cause they don't look like ours. Ours are round headed with a screwdriver slot.

And if you didn't know what size yours is, how do you it's not a 160 already? pop the bowl off and take it out. If you have to ride it to get the parts, take some measurements, note the numbers and put it back.

1st time getting the bowl off can be hard, use the right screwdriver JIS#2 or you'll need to grip the head with a pair of vice grips.

Here's the post on carb spec's...
http://suzukisavage.com/cgi-bin/YaBB.pl?num=1098869040/5#5

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jabman Senior Member Offline Posts: 411 England Gender:	Re: Backfire issues.. Reply #14 - 09/27/10 at 14:25:59 there are plenty of places that sell the right size jets you need in the UK i can tell yer if ya want?
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