FORUM

Notifications
Clear all

Elevated Engine Idle RPM

33 Posts
3 Users
0 Likes
7,506 Views
Richard W
(@wobbly)
Posts: 2529
Member
 

Carbs are balanced at 5000 RPM and engine runs pretty smooth now.

CV type carbs will automatically balance themselves at high RPM. That's one of the design goals and attributes of the CV. But how's the balance looking at 1000 and 1800 RPM ? That's what really matters.

Did you replace both of the idle jets ? They are typically #40 or #45 and too small to clean.

Owning an old Airhead is easy.
Keeping an old Airhead running great is the true test.

 
Posted : 10/14/2019 16:54
Lawrence Ayotte
(@8244)
Posts: 49
Eminent Member
 

I found that my 84 R65 ran poorly cold and seemed breathless at higher rpm when set up with stock settings in the carbs. I did a minor muffler mod per Snowbum’s recommendations which likely didn’t help with the lean symptoms. After playing around with jets and adjustments, I ended up with the needles one notch higher and the main jets two sizes larger. Running perfectly now and it’s reliably getting 46-47 mpg. I despise e10 fuel, it’s a crock!!

 
Posted : 10/15/2019 10:55
Richard W
(@wobbly)
Posts: 2529
Member
 

Thanks, Mr 8244. Ethanol fuels do contain less energy and so many people find what you said to be true, myself included. Additionally, comparison of jet tables between European and American bikes (same year, same model) will usually show the European models with larger jet sizes simply due to US EPA regs kicking in between the mid-1970's and early 1980's. So US models were being leaned out on the much better fuels we had in the 1980's, then came Unleaded followed by Unleaded with Ethanol.

However, because "jetting" an engine depends on everything else being perfect, it has to be the last step taken in tuning. While Mr 895 may need this additional help as Step #10 to get optimal performance, first he has to get the bike that used to run good, to begin running good again, which is Step #8. As I understand it, this issue simply showed up one day, which indicates a repair is needed.

Bottom Line: These things have to be done in the correct order.

Owning an old Airhead is easy.
Keeping an old Airhead running great is the true test.

 
Posted : 10/15/2019 11:43
Page 3 / 3

Advertisement

Scroll to top