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Message started by Tocsik on 06/21/14 at 19:19:45

Title: High-altitude tuning after carb cleaning
Post by Tocsik on 06/21/14 at 19:19:45

'08 with ~3K miles purchased a few weeks ago. I'm in Denver at mile-high altitude. Had some sputtering in the mid range so decided to clean the carb as a first step.

Carb looked OK to the naked eye but you never know about varnish or small particles so I broke it down, sprayed with carb cleaner and then air blasted everything. Cleaned the TEV and main diaphragm with dish soap.

I went ahead and did the white spacer while the carb was out and apart. Replaced stock spacer with 2 #4 nylon washers from Ace. Looked to be about half the thickness of stock.

Got it all back together and it starts and idles real nice. But, on a test ride, there's just no power. No mid or top end.

Tomorrow I'm taking the jet needle back to stock but wanted to get some input from the forum also. Only possibly oddity is I had to replace the 2 lockplate screws on the needle since the heads got a little buggered on the way out. Replacements are computer screws that fit perfect except the heads are just a little bigger in diameter (sort of a mini flange screw with a built-in washer). One of the screw heads just slightly covers one corner of one of the holes in the needle lockplate. Just the slightest overlap.

Bike is stock other than Raptor and Dyna and had pretty good top end before I cleaned it.

Thanks for any words of wisdom. I'm hoping to not pull the carb all the way back out. That really wasn't easy.

Title: Re: Need some guidance after carb cleaning
Post by S-P on 06/21/14 at 20:05:47

Do you know the size of your main jet? If it is 47.5 you might be running lean.

Title: Re: Need some guidance after carb cleaning
Post by Tocsik on 06/22/14 at 11:02:13

383F2E3D2E253B2A3E274B0 wrote:

Do you know the size of your main jet? If it is 47.5 you might be running lean.

I rolled back the nylon spacer to the stock space and it's running pretty good this morning. I do notice that at lower RPM's (sort of cruising speeds) there's a little bit of smoothing-out with the choke pulled out slightly. Mix screw is about 2.5 turns.

I think the jet's a 45. Maybe a PO dropped it down for our altitude. I wrote down the numbers on the brass bits while I had the carb apart but I think that was the pilot air jet in the top of the carb, not the one in the bowl. I have a note about the main being 145. Might have to drain the bowl, remove it and look up in there with a mirror. :-/
Plug might agree with you. There's a little brown but I suppose it should be a little bit more.

Title: Re: Need some guidance after carb cleaning
Post by S-P on 06/22/14 at 14:36:15

Looks a little lean. Hopefully others on the forum will know more about high altitude carb tuning. I'd suggest editing your "topic header" to "high altitude carb jetting" or something like that.

Title: Re: High-altitude tuning after carb cleaning
Post by Tocsik on 06/23/14 at 08:10:48

Thanks S-P, I'm giving that a shot.

Anyone have general guidelines/starting points for tuning at about 5K altitude? White spacer mod was a total bust for me!

Should both jets be changed/up-sized at the same time or is OK to just work the main a little higher?

Currently stock airbox and Dyna exhaust but I'm considering the free-flow air filter (Poly-fil Nu-Foam) in the stock airbox (http://suzukisavage.com/cgi-bin/YaBB.pl?num=1183640744/0).

Title: Re: High-altitude tuning after carb cleaning
Post by Serowbot on 06/23/14 at 08:23:44

If you're doing a filter, just wait with tuning...

I think I'd start with just the main...

I'm pretty happy with a #150/#50 at 2600ft... with a Dyna and K/N slip-in filter...
...(2/3 spacer,... not sure if it needed it)... I may change back to stock spacing someday...

Title: Re: High-altitude tuning after carb cleaning
Post by HJH on 06/24/14 at 16:11:04

I'm in Cheyenne, at 6,000 feet, and now have one of Lancer's carbs and a UFO, but when stock, I had a 52.5 pilot, 3 washers on the needle, and a 147.5 main. Ran well, with a tan plug, and 45-50 mpg, depending on my right wrist.
For those who might be trying to tune a VM carb at altitude, with a VM carb I have a Q2 needle with the clip in the middle slot(3), a 12.5 pilot since soldering the pilot jet shut didn't work, a 170 main, two turns out on the air screw, a B7(one step hotter) plug, and the UFO in the leanest position. With the needle in position 2, mileage was 44mpg, now it is 48mpg. I am extremely sick of removing the seat and tank, and would like to kick the rear end of the guy who drilled the holes in the Corbin seat that didn't match the holes in the Suzuki. But the bike runs extremely well, accelerates as Lancer said it would, and has hit 90. The stock bike struggled to get 80. I have zero backfires, but no choke is required to start it.