Only 3/4 throttle

[Keepi time]

I have a 1989 90 hp Johnson v4. I had the timing set at a local marina. Problem is that my throttle linkage or carburetor is not getting to full throttle when I push the controls all the way forward. I am only getting about 4900 rpm's at wot. I tried to adjust the cam follower assembly to push the throttle linkage more but it throws the timing out of wack. How can I gain more movement to open the butterflies without throwing the timing out. It seems that they should have set the carbs to open fully first and then sync everything. Seems like they did something wrong. Any help is greatly appreciated.

 

[SparkieBoat]

Re: Only 3/4 throttle

yep they did it wrong, do it like you think it should be done..make sure to check your timing after wards. If you have a manual it will tell you the proper link and sync procedure.

 

[Keepi time]

Re: Only 3/4 throttle

Thanks for the rely! Can I set the cam follower pickup to advance my throttle all the way and then adjust the spark advance timing? I have that crappy clymer manual that has pics about as good as a first year model black and white tv. I sort of understand everything I will have to set the wot timing when I get to the water this weekend. Sucks I paid these guys 100 bucks for nothing. Definitely won't take it back to those guys. Thanks again spark!

 

[emdsapmgr]

Re: Only 3/4 throttle

If you disconnect the throttle cable at the engine end, can you manually advance the throttle lever so that the carb butterflys fully open? If so, then the throttle cable needs to be adjusted.

 

[Keepi time]

Re: Only 3/4 throttle

@emdsapmgr, I did that but the eccentric that rotates the rolloer cam to advance the throttle lever is all the way to the stop, i can't advance anymore. The only way I can see getting the throttle lever to open all the way is to move the adjustable nut on the essentric, which advances my timing, all the way forward, there is no more adjustment when I do this, it's all the way at the end. Thought maybe adjusting the throttle arm on the carberator cam but , that has limited adjustments and don't want to mess up it's position to the roller cam. Then I thought if I move the eccentric to open the throttle lever all the way, I would just need to adjust the sprak advance at the top to get the timing in agreement with my essentric adjustment. I know I should probably take it somewher but after getting it done wrong the first time, I don't really trust anyone else to do it. Does anyone have a picture of their essentric adjustment so I can see about where your is set? thanks for all your help, the weekend is getting closer and time is winding down, hate to run 3/4 throttle all weekend, would love to open this thing up one time.

 

[emdsapmgr]

Re: Only 3/4 throttle

If it's not the throttle cable, it's the sync and link that's the problem. Just what you've been thinking and struggling with. That year/model uses a different cam/link system from the ones a few years earlier. Probably best if you have a factory service manual to sync and link from. As you know, it's difficult enough to try to describe the process without a picture.

 

[Keepi time]

Re: Only 3/4 throttle

No where I can order an actual factory service manual? That Clymer is horrible!

 

[SparkieBoat]

Re: Only 3/4 throttle

http://forums.iboats.com/showthread.php?t=301361 Also make sure you are getting full range of motion in your throttle cable, sometimes the cable will begin to break down inside the sleeve and give less range of motion. But i suspect a proper link and sync is what you need. you should be able to disconnect the throttle cable, then do a proper link and sync then reconnect/adjust the throttle cable.

 

[Keepi time]

Re: Only 3/4 throttle

Thank you! I will keep you all posted on the results, I'll just have to wait for the manual. I hope this one is more detailed than the Clymer.

Thanks again!

 

[Keepi time]

Re: Only 3/4 throttle

Well guys problem solved. It was exactly what I thought. Moving that cam eccentric gave me full throttle. 5600 rpm's at 36 mph. What a great feeling to realize how something works. Change my water pump today as well. Had a great day on the water today. Oh yeah seafoam is a wonderful thing by the way. Engine has been purring!!!!

 

[SparkieBoat]

Re: Only 3/4 throttle

sea foam is great..also stabil makes a marine/ethanol formula that works well for fuel storage. glad you got it.