RESTO Mikuni carburetors tuning

Note: This site contains eBay affiliate links for which SeaDooForum.com may be compensated
Status
Not open for further replies.
M

MariusAlecsa

New Member
I have a Sea-Doo Challenger 1800 1999 model. 787 rotex engines. Does anyone know a good mechanic in the Phoenix AZ area that will know how to tune the carbs? It works great untill the temperature gets over 100°. when the temperature gets over 100° my right engine does not want to give me the last 400 RPM which makes a world of difference. Thank you for all your help in advance.
 
I’ll have them check the compression as well as soon as I find someone. The boat is in pristine condition and barely used. I messed with the idle screw and I am sure this threw it off. It worked great before than.
 
MariusAlecsa said:
I have a Sea-Doo Challenger 1800 1999 model. 787 rotex engines. Does anyone know a good mechanic in the Phoenix AZ area that will know how to tune the carbs? It works great untill the temperature gets over 100°. when the temperature gets over 100° my right engine does not want to give me the last 400 RPM which makes a world of difference. Thank you for all your help in advance.
Click to expand...
I have the same boat year and all. Bought it 2 months ago. I need to have my carbs tuned as well. Virginia area. Seems like even the Sea-Doo shops in this area have stopped working on carbs and two-strokes on these older machines.
 
The carbs really should run pretty well at the factory settings. I’d suspect that they need a good cleaning and rebuild before they need to be tuned. I think you’re far more likely having someone screw up the adjustments rather than fix them...
 
What are the factory settings for each screw? Boat is 20 years old. Been cleaned and rebuilt, just want to make sure it's optimum.
 
Factory settings are 1-1/2 turn out from closed on the low speed and closed on the high speed. You should have a 1.5 needle and a popoff between 36-40.
 
Just rebuild my carbs last year. Worked fine till I adjusted the idle. I travel a lot for work and I do t have much time left to work on it. I’ll try to mess with them first chance I get unless I can find someone that knows what they are doing.

I called sea-doo and other shops and no one seems to wanna touch them.
 
Checked out the compression in all cylinders and looking good. I adjusted the low speed screws to 1.5 turns and high speed closed.
 
The low speed screws had 1/4 variation from factory setting. Gonna put them back on tonight and head to the lake tomorrow for a test run. If you have any more ideas please advice. I will post updates tomorrow. Thank you all for your help.
 
Came back from the lake today and it works much better. However... when I punch both throttles to full, both engines goes to 7200 RPM,s and after a second or 2 the right engine backs up to 6200 RPM and than gradually back to 7200 as it comes out of the water. Any Ideas. Please help.

I am sure this might not be related but my boat pulls to the left at all times. I am always correcting to the right. Pretty sure the boat is not going straight. Any advice would help.
 
7200 is pretty high for these engines, 6900 is about normal.

From a dead stop it sounds like you are getting some cavitation which is pretty normal if you just floor it from a dead stop.
 
Status
Not open for further replies.

Similar threads

CantComplain
2001 Utopia Bilge Pump
Replies
2
Views
461
CantComplain
CantComplain
SoCal_GTR
  • Locked
Greetings!! Just picked up some GTR's, then......
Replies
1
Views
401
GTR 215
GTR 215
W
  • Locked
Rotax 717 Cylinder Pitted
Replies
10
Views
718
WhiteZombie
W
C
  • Locked
Carb rebuild
Replies
4
Views
336
Clizano12
C
R
  • Locked
2000 XP bogs / surges at high rpm
Replies
3
Views
742
RC951
R
Back
Top