Throttle bodies - think it's clicked

[Dr Bones]

Sorry, but I've never had a bike with fuel injection. I've stripped and tuned plenty of carbs though.

I think I am right in saying that the brass air screws, bleed air past the butterflies at idle and at closed / very small throttle openings. Once the butterflies are more than about 1/8 open then they have little or no effect. Hence balancing the TB at idle with the brass screws, then at 1500rpm with the right throttle screw.

I'm comparing this to idle air screws on carbs.

 

[(RIP) Kaister]

pretty much

 

[Canuck]

Sorry, but I've never had a bike with fuel injection. I've stripped and tuned plenty of carbs though.

I think I am right in saying that the brass air screws, bleed air past the butterflies at idle and at closed / very small throttle openings. Once the butterflies are more than about 1/8 open then they have little or no effect. Hence balancing the TB at idle with the brass screws, then at 1500rpm with the right throttle screw.

I'm comparing this to idle air screws on carbs.

Don't just use the right side.... did you read that on that american site?

 

[Canuck]

As stated by Steptoe...

Don't adjust the idle with the cable adjusters. You must have play in both throttle cables. Don't get hung up on trying to get 2mm, it's not really important how much in the great scheme of things, anything between 1mm and 5 mm.

Balance the idle with the bbs, again it doesn't matter if there's a difference between how many turns out they are, just get them even on the guages.

Then balance the throttles under load by the cable adjusters, working on the side that doesn't tighten the cable i.e. adjust the side that needs to be loosened to balance the set up.

 

[Ugly Cow]

kaister, that picture of that poor woman (is it your wife) I think using a washer board, please get her a washing machine then she would not be so tense and tired. I don't know but to be honest she may be more receptive to your advances. she looks shatered.

 

[uncle dick]

Sorry, but I've never had a bike with fuel injection. I've stripped and tuned plenty of carbs though.

I think I am right in saying that the brass air screws, bleed air past the butterflies at idle and at closed / very small throttle openings. Once the butterflies are more than about 1/8 open then they have little or no effect. Hence balancing the TB at idle with the brass screws, then at 1500rpm with the right throttle screw.

I'm comparing this to idle air screws on carbs.

Do you have single or twin cable set up? It makes a difference.

 

[Canuck]

Do you have single or twin cable set up? It makes a difference.

I think the bike is from 99... so twin methinks.

 

[Dr Bones]

I think the bike is from 99... so twin methinks.

It's a 97 so I'm not sure, as I said it's a new bike for me so I'm just working things out.

I've been using the Oilheads guide (page 21 on), so I've been using the brass air screws to balance the TBs at idle and set the idel speed then, just the right throttle screw to balance then at just off idle. It says the brass screws shouldn't be more than half a turn different and only states to adjust the right throttle screw.

am I doing something wrong ?

 

[Steptoe]

It says the brass screws shouldn't be more than half a turn different and only states to adjust the right throttle screw.

am I doing something wrong ?

If it idles evenly it doen't matter what the difference is in the screws. Especially on a bike 14 years old.

Adjust any side you like. It's your bike, the idea is to get the bike to suit what YOU want, not some pillock who enjoys overcomplicating things and making a ten minute job into a war and peace novel on the internet.

 

[Canuck]

Well mines a '97 and it has two cables... doesn't mean your does though I suppose. I wouldn't worry about hte difference between bbs turns... just get the idle set.

If you have the old single cable then mattw has/had the same setup. I think its a pita to get perfect so he set it to be spot on at 4000rpm... I guess thats where he spends the most time driving. Dont ask he how to best set up that though... never done it myself.

 

[Dr Bones]

Thanks for the advice people, you know how it is... new bike, not sure how things should be and don't want to mess something and end up with an expensive bill. I'm going to have another go balancing the TB's at the weekend. I've had engines apart and back together successfully, so this one isn't going to beat me.

 

[steve'o]

I'm about to do this too with the service next week. Am I right to say that on the tb's there is a particular screw NOT to adjust because its some kind of factory setting that shouldn't be messed with?

Standing by to be shot down in flames....

 

[Canuck]

Well the big brass ones (that you can see when sitting on the bike but with your feet on the ground) are fine... often referred to as big brass screws (BBS) or idle air bypass screws as shown in the picture... they adjust your rpm at idle . The other bits you use are where the throttle cables attach to the throttle bodies... there will be a little nut sitting on top that needs to be loosened ... then you can adjust the bowden cable adjuster with your fingers. I think tend to hold the bits that I've adjusted with my fingers with a set of pliers while I tighten the nut with a small spanner or what ever you call them.

The things you don't want to touch are the butterflies... But if you get to this point you've definately gone wrong with your TB sync.

 

[Dr Bones]

Well got the TB balanced both at idle and at 1500rpm. Setting the CO was a game though. With the beige cat code plug fitted to the bike the CO pot only seems to want to go up to 1.8% and the idle was still pretty lumpy. So I played around with the various CPP jumperings (including no CPP - bike started but stalled immediately). I ended up with pins 30 and 87 (2 and 6 on the socket) bridged which I believe is the same as a yellow CPP, With this setting the CO pot did nothing, but the bike idled very smoothly and pulled very well throughout the rev range, with only a hint of surging lower down.

(FYI - The beige CPP is pins 30 and 87a)

Anyone know where the yellow CPP is normally fitted to this bike (worldwide) ?

 

[Dr Bones]

Forgot to add, before I did the TB balance I set the tPS to 0.37v, it had been set to 0.22v. This seemed to help a little by itself.