TW200 Forum banner

1 - 12 of 12 Posts

·
Registered
Joined
·
33 Posts
Discussion Starter #1
Hey everybody, just not sure where i need to go with my jetting. like i said i have an 87 tdub and i opened it up to find it jetted at 114 and 40.

i bought it used and it ran pretty good in boise which is around 3k feet. It really did lose power though around 6k feet as it seems they'll do. so i just moved to denver and it'll run but it will only idle with the choke on. i'm not a carb guy by the biggest stretch of the imagination so can somebody or a couple people make some recommendations as to where to start.

thanks for any help!! i'll be probably a good 60/40 split between commuting and trails but i don't really want to have to rejet every time i head into the mountains. thanks again.

brandon
 

·
Registered
Joined
·
13,401 Posts
I'll have to let the carb experts chim in on which way to go on jetting. Living in the Treasure Valley myself, I didn't feel the need to change carb settings on my TW from the stock configuration, but Denver is quite a bit higher than here.

However, one thing I can comment on from what you're describing and possibly a short term solution to your idle issue, is to adjust your carb idle adjustment. When I ride up in altitude, I routinely adjust my idle speed. Another thing I did on a suggestion from the old old forum, was to drill a few holes on my side air filter cover. I drilled a few holes in various area's of my cover. I now place black tape over the holes when I'm riding down here in the valley, and uncover them when I get above 5,000ft. However, you would have to be comfortable doing this to your air filter cover and is not really the long term solution you need, but it works!

Sorry I can't be of much more help, but I just haven't paid a ton of attention to changing my jets and would have to do a bunch of research on my own to understand exactly what to do. Lots of good info in the sticky portion of this thread you may want to view. Good luck
 

·
Registered
Joined
·
33 Posts
Discussion Starter #4
thanks Admiral. yeah, i've seen the stuff with the holes in the box and i spent a lot of time reading the posts about carb jetting on here and other sites. everybody says that the stock jets are good but that the stock jets are 114 and 40 in the 87. so i wasn't sure what would be the deal. did i need to go down in my jetting and i don't know what the rule of thumb is for starting. should i go down just 5 or 10 or what. if anybody else can give a suggestion as well i'd appreciate it.

thanks again for your response. i'll check the idle adjustment too. thanks.
 

·
Registered
Joined
·
2 Posts
I'm interested in this too. I'm in Albuquerque and my TW runs fine here (5200 feet) but when I went riding up in Pagosa Springs and when I got around 8000 feet I was getting hesitation then acceleration when opening the throttle quick. When I got up around another 500 to 1000 feet it got a little worst and to the point it stalled me out a couple times on the slower more technical things like big rocks.

Is moving down on the number for the jet leaning it out?
 

·
Registered
Joined
·
33 Posts
Discussion Starter #7
moresnow- yeah but i don't know what how the altitude correlates with the jet size. like if i'm running a 114 and 40 and came up 3k feet, do i need to go down to a 112 per thousand foot of elevation gain? per 2k feet? per 3k feet?

do i have to drop my idle jet at the same time and the same rate or leave it the same?

if it won't idle well at this altitude do i start by just changing the idle jet?

that's what i'm trying to find out before i put everything back together since taking the carb off and on is kind of a pain in the butt.
 

·
Registered
Joined
·
3,477 Posts
moresnow- yeah but i don't know what how the altitude correlates with the jet size. like if i'm running a 114 and 40 and came up 3k feet, do i need to go down to a 112 per thousand foot of elevation gain? per 2k feet? per 3k feet?

do i have to drop my idle jet at the same time and the same rate or leave it the same?

if it won't idle well at this altitude do i start by just changing the idle jet?

that's what i'm trying to find out before i put everything back together since taking the carb off and on is kind of a pain in the butt.
Unfortunately, it's not possible to give more than a rough idea of which jet is exactly right for which altitude, due to individual variations in engines and carbs.
Rough Idea:
If you run a 114 in the pre-2001 TW's at sea level, it should be OK up to about 5,000
A 112 should be OK from 3,000 to 8,000.
A 110 from 6,000 to 12,000.

I have a 2010, so these numbers may be off a little, maybe a Colorado guy with a pre 2001 would chime in.

There is very little need to change the idle JET unless you LIVE above 10,000.....the idle screw will deal with it. I don't adjust my idle screw until I get above 10,000. I bump up the idle RPM first, then I'll turn the idle screw in a half turn at a time until it runs better (leaner).

The later models seem to have more altitude tolerance. I've run mine with the stock 126 jet from Death Valley to 12,000 in the Rockies without any real problems other than loss of power. (which I would deal with by a jet change if I was going to be there a week or so.)

If you are not going to spend a lot of time above 5,000, you should be OK up to 8,000 for a few hours with a 114, unless you are tackling some technical uphill sections requiring slow 1st gear operation; this is where the possibility of bogging can bite you. If you DO get into an over rich situation, the first place you will notice it is in a full throttle run up a gentle hill in 5th gear. The bike may continue to run fine at lower throttle settings or gears. Not really a problem on the trail except for the above situation.

Bottom line: If you LIVE above 5,000, it's worth getting the jetting just right....if you are only visiting, you should be able to leave the 114 in and just fiddle with the idle speed and screw. (At least until above 10,000)

EDIT: Oops, I just re-read your original post, so at 5280 feet you WILL want to change.....maybe a 110 will turn out to be the best compromise, a tad lean in Denver but good all the way to 12,000. Someone with better knowledge of the 87's should post on this.
 

·
Registered
Joined
·
33 Posts
Discussion Starter #9
that was perfect!!! Thank you thank you!! that was exactly what i needed to know! thanks for the help! i'll be getting the new jet today! :) thanks again! sounds like everybody on here is from idaho! MAN!! I REALLLLLY miss it...this place just ain't idahome........thanks again.

brandon
 

·
Registered
Joined
·
33 Posts
Discussion Starter #10
Can anybody post a link to a jet interchangeability chart or post? The tks are hard to find. Can i use another brand? If so what sizes would correlate to the tk jets? Thanks again everybody!
 
1 - 12 of 12 Posts
Top