Can anyone suggest a good visual or written resource for proper settings for the internal throttle grip/handle set up? My cables seem to be fine but something has slipped or was not set right inside the throttle grip where the two cables connect. For sometime I felt I could not open up the throttle all the way. It got worse and i had to ride home at night pulling on one carb cable with one hand steering with the other and shifting in between or not at all... the cog that the cables are connected to has to be set at a certain position it seems... just what is that position...
I'm not aware of a shortcut to this setting, but here's how I do it...
1) This step is very important. Remove the cable cap and the twistgrip from the handlebars. Wipe the entire exposed end of the handlebar with grease. Also fill the gear teeth on the end of the twist grip with grease. Slide the twistgrip back over the handle bar and spin the twistgrip several times to distribute the grease.
2) With the cable cap removed, the first item to set is the radial position of the twist grip. The cable cap has a boss protruding downward that 1) physically attaches the twistgrip to the bike, AND 2) forms the hard stop for the twist grip when cutting back on the throttle. So the twist grip itself has a definite, highly defined insertion and rotational position.
3) With the twistgrip in that position, fit the bevel gear. Place it in a position that best removes about 90% of the cable slack. You must have several MM of throttle cable slack. Taut cables will not allow idle speed adjustments.
4) Secure the cable cap in place. Everything else is done at the carb end of the cables during carb balancing.
Hope this helps.
Owning an old Airhead is easy.
Keeping an old Airhead running great is the true test.
Richard - thanks for the instructions. I went through the process 4-5 times. All went well but the twist grip gear appears to be worn from year of use and slips where the worn edges of the gear are... See photos. Looks like this has been an issue before for previous owners as the cable cap set screw is pretty buggered up from attempts to crank it down and i assume put more pressure on the twist grip... see photos... If you think this is correct I suppose I need to find a replacement twist grip - any suggestions?
Thanks again,
DS
@16606 I'm not an expert, but have serviced maybe 8-10 twist grips on models from 1975 to 1988 and have never seen that much wear. I'd replace both parts. Lightly used parts should not be an issue.
Then, before applying the grease, measure the vertical clearance allowed for the "Throttle Cable Pulley". My thinking is the twist grip is not allowed much lateral movement due to the engagement of the boss protruding downward from the "Top Cover". Therefore any wear is most likely the result of excess vertical movement of (clearance in) the Pulley.
If the replacement parts exhibit excess clearance, then shims atop the Pulley may be required. A shim will force the Pulley to a lower position and thus greater gear tooth engagement. While it might be easier to prototype with materials like plastic milk jug, once the optimal thickness is discovered, then metal parts should be fabricated.
You have an interesting issue. Hope this helps.
Owning an old Airhead is easy.
Keeping an old Airhead running great is the true test.
@wobbly Thanks again for your take on this. I will shop for replacement parts.
DS
it is completely worn out. replace the throttle tube and the toothed gear as a set.
both of these have an index line cast on them. on assembly simply line up the lines. see manual.
be generous with the grease. on an open bike a waterproof grease is desirable. regrease yearly for longest life.
to salvage the grip from the old throttle tube use alcohol. then apply some (70% or better) between the outer edge of the grip and the tube, rolling that edge back with your fingers. if vocabulary is required don't hesitate. once the alcohol has penetrated under the grip enough it will come off abruptly.
Thanks for the input and instructions. I have ordered used parts from Bobs.
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