Would altitude affect performance?

nelly · Post by **nelly** » Wed Jun 29, 2005 11:16 pm

Hi guys,
Spree is starting and idling fine, but when I give her full throttle, it certainly doesn't respond very well. Doesn't rev up and down like a two stroke should.

Could altitude be an issue? Here in Calgary were @ 1140 meters above sea level (3750 ft).

I notice that the plug looks kinda wet and oily/black. I assume this is too rich so I will try adjusting the throttle needle setting a little leaner.

I took the muffler off thinking that perhaps it was plugging up the exhaust, but there's no real difference in 'reving'.

So she idles fine, I just can't ride her cause there's no real power. I've been looking at other posts re. power, looks like it could be compression if not the needle and running rich? Clutch perhaps?

Steve

burnt_toast · Post by **burnt_toast** » Thu Jun 30, 2005 12:58 am

If you can tell a difference in how the motor reacts at higher speed, then I dont think that its clutch related. it may be rich and that may be a side affect, but im not sure. think i saw it on a 2stroke page, ill try to find it.

ferchja · Post by **ferchja** » Thu Jun 30, 2005 12:58 am

Clutch has nothing to do with reving, unless the engine just races and the rear doesn't move under load (i.e. sounds like the engine is in neutral)

Altitude would limit oxygen and pressure so I would expect your are just running too rich. Try the 3rd notch on the needle. Your local motorcycle shop may be able to give some general advice on settings to keep in mind when dealing with an altitude of 4k ft.

burnt_toast · Post by **burnt_toast** » Thu Jun 30, 2005 1:01 am

found it! here u go:

If your engine does not rev up well, and stutters or sputters, like when it is cold with the choke on, the engine is running too rich. (too much fuel).

http://www.scootertherapy.com/runslowpage.html

good site for troubleshooting too.

Post by **noiseguy** » Thu Jun 30, 2005 10:01 am

Check the size of your main jet. Should be a #65 if stock.

Higher altitude will cause you to run rich. I would contact your local cycle shop about rejetting. You would want to run a smaller jet than stock.

Check to see if you're using the right heat range plug for your riding style.

Removing the exhaust is not the same as checking if it's plugged, unless the scoot won't start at all.

Cheers.

nelly · Post by **nelly** » Thu Jun 30, 2005 9:14 pm

I adjusted the needle - it was set on the 3rd upper ring already! So I bumped it up to the 2nd notch. Sounds a little better and idles smoother, but no difference in power. No big suprise - I didn't think a millimetre increase on the needle would suddenly give me my power back.

It's kinda tough having never hear a properly running Spree whether or not mine is running and reacting properly when the throttle is cranked up and down.......I'm going to try and record a short movie with sound of the beast idling and then with full throttle, maybe someone can diagnose the problem for me that way???

As I mentioned earlier, I removed the muffler, gave it a good shake - nothing sounds like there's loose dirt or anything in there plugging it. I can blow air through it easy too. Plus when it is running there's a pretty good 'puff' of exhaust that comes out. d*** this is frustrating. I haven't been able to find a place to rent out a commpression gauge yet, (don't really want to spend the $40 for a 15 second test) so it could still be compression.

Other than compression is there anything else to check? I never really hear much about the reed valves - do these ever need cleaning?

Going to try to record the short movie and take a look at the cylinder for carbon.

Sorry for the rambling post.
Steve

nelly · Post by **nelly** » Thu Jun 30, 2005 10:07 pm

Don't know if this movie will work or not, but you can see/hear that it doesn't seem to be reving up to it's full potential

And least it doesn't seem like it to me.

Can anyone tell by the sound what might be wrong - again, idles fine just very little power......
thanks guys,

http://www.knapmanstudios.com/images/spree.mov

vette76 · Post by **vette76** » Thu Jun 30, 2005 10:36 pm

doesnt sound too good. does ur rear tire move free? that should at least be turning a little. try taking off the drive belt and see if it revvs higher. could just be the sound quality but that engine doesnt sound right.check to make sure the clutch+ tire spin and work together freely. the parking brake wasnt on shooting this vid was it?

ferchja · Post by **ferchja** » Thu Jun 30, 2005 11:55 pm

Take the parking brake off and try the movie again. The load and noise you hear is the clutch fighting the brake, and then the motor bogging down with no where to go. Other than that it sounds fine at idle, it sounds like it is running a little fast at idle, but this cannot be determined since the parking brake was on. The idle noise and clicking is the engine wanting to throttle up but being held back by the parking brake.

The fact that the motor doesn't quit under a complete load with the brake makes me believe that it is fine.

nelly · Post by **nelly** » Fri Jul 01, 2005 12:08 am

Sorry guys - yes the parking brake was on - I noticed that after I uploaded it - will try again tomorrow and repost........

Post by **noiseguy** » Fri Jul 01, 2005 12:50 pm

$40 Cnd sounds about right to buy. Don't you have auto parts stores that offer "free tool rentals?" These guys will let you use the tool and bring it back free of charge. We have these in the States (Murrays, Pep Boys, etc.)

nelly · Post by **nelly** » Fri Jul 01, 2005 3:57 pm

Well.....reposted the movie. This time with the brake off. Should it be reving higher than that? Lots of pressure coming out of the tail pipe. Just doesn't sound quite right to me.

http://www.knapmanstudios.com/images/spree.mov

So far......
- I've removed the pipe and run it - no difference (just a * of a lot louder). So thinking muffler is not plugged/affecting.

- Looked down the exhaust 'manifold' with the pipe off - there's definitely some black coating in there, but nothing that's seems to really be restricting exhaust flow.

- Idles very well

- Still have to test the compression as soon as I find a rentable tool.

- Adjusted the throttle needle setting (on the first notch now, but will probably drop it down to the 2nd), seems to improve the idling (a little smoother) and the spark plug is not wet anymore when removed.

Any other suggestions?
Thanks again everyone.

nelly · Post by **nelly** » Fri Jul 01, 2005 4:48 pm

OK - I figured, if it's getting gas, exhaust is fine, then it must be something to do with air flow. Took the air filter out, cleaned it again, oiled it up again, insterted and closed up the air box - still no good.

Left the freshly cleaned/oiled airfilter in box, removed lid......runs like a champ, and pulled me around our street quite easily!!!

So what does this tell me when it runs fine without the airfilter cover? Something else must need to be tweaked right??

Steve

EDIT - Should mention that it ran really well, dragging me around the nieghbourhood at 40km/hr for about 5 minutes, then, it started to bog out with the throttle full blast, and would only stay running if I let off the gas. This is still with the air filter lid off.

Will check the jet number Jet is a #68

Took carb apart again and all is clear. Since this was a local Spree, I would be suprised if the I'd need to try a smaller jet?? I would think it was running fine with the #68 before it was set aside? Don't know for sure though.

vette76 · Post by **vette76** » Fri Jul 01, 2005 6:13 pm

try opening up the air screw. it sounds like u have the wrong jet. i would try really cleaning the carb and blowing out all passages with compressed air.

ferchja · Post by **ferchja** » Fri Jul 01, 2005 9:52 pm

Sounds like you are running rich. Since you opened the box the more air flow matched the excess fuel. The compression may be the issue. Vette is right, something sounds a miss. It may be an issue with compression, and a vacuum leak/gas leak with the bystarter. If you will not be testing the compression for awhile, let it idle and then pull the bystarter and plug it with your thumb and run it to full throttle.

I had a rich condition with the old bystarter and after replacing it is near new. I think my old bystarter did not seal the fuel and air off when warm and caused it to cough and sputter. That was my situation.

The mechanical is a lot easier then electrical to fix since you can measure all of it and just seal it.

Good luck

Honda Spree and Elite 50 Forums

Would altitude affect performance?

Would altitude affect performance?

Much, much better w/out air filter