1993 85 hp C85TLRR yamaha Carb rebuild and prob question

[shackle101]

Hi all I'm planning on rebuilding the 3 carbs (I got the carb kti) on my 85 hp Yamaha and I've never adjusted the carbs on a boat outboard before. What would be the Ideal RPM for idle running when adjusting the carbs for this engine? I certainly don't want them to be running lean. If there is anything else or suggestions you guys may have to help me in the long run please feel free to share.

Also it doesn't have a tach meter so I'm trying two products from amazon one that's a laser and the other that attaches to smart plug cable (i think) has anyone done that method before is it pretty accurate? I heard you can put reflective tape on the fly wheel to get the RPM with the laser.

Also I purchased a new prop for it awhile back (Yamaha 6E5-45945-01-00; AL.PROP 13-1/4X17; 6E5459450100) I wanted to know if this was my best option for the best speed/pulling power. I get pretty close to 40mph when the water is pefect (maybe 36-38 mph) is that all I should be expecting for with the 85hp? The boat is 18ft typical fish and ski v hull.

Thanks!

 

[shackle101]

Re: 1993 85 hp C85TLRR yamaha Carb rebuild and prob question

Meant spark plug cable, and carb kit won't let me edit the post for some reason .

 

[robert graham]

Re: 1993 85 hp C85TLRR yamaha Carb rebuild and prob question

Are you sure the carbs need re-building? When you disassemble the carbs don't mix up the jets, as they may be different sizes from carb to carb. There's a carb linq and sync procedure in the Yamaha Manual(You will need a manual). The idle speed is about 750RPM's, warm motor. You should prop for a wide open throttle of about 5500RPM's, give or take a couple of hundred. If your wide open throttle was say, 4500RPM's then your prop could be wrong and not good for motor. Maybe you can install a real tachometer which is very nice to have for future running efficiency. Good Luck!

 

[Silvertip]

Re: 1993 85 hp C85TLRR yamaha Carb rebuild and prob question

There are two adjustments to consider: 1) idle mixture adjusts the fuel/air mixture at idle and has nothing to do with idle speed. 2) Idle speed is a mechanical adjustment that determines how fast the engine idles in neutral. They are two very different adjustments. #1 is the one that controls rich/lean at idle. The high speed jets are fixed and control the fuel/air mixture at high speed.

 

[shackle101]

Re: 1993 85 hp C85TLRR yamaha Carb rebuild and prob question

I have't took the carbs apart yet, but I went ahead a purchased the carb kit from Yamaha which all the jets/ect look identical. Do you think I should just use just some parts (floats/gaskets) from the kit and just ultra sonic clean the carbs rather then full rebuild? The carbs are leaking fuel from the intake you can see the fuel standing inside. I seen a manual for 86-96 motors but I heard it's very basic does I wonder if it will even cover carbs in detail. Here: http://www.iboats.com/Yamaha-Outboard-Manuals-Repair-Service-Maintenance/dm/view_id.251026

The OEM Tach cost like $150+ seems a bit high for me lol. Boating isn't cheap I know! ;-)

Are you sure the carbs need re-building? When you disassemble the carbs don't mix up the jets, as they may be different sizes from carb to carb. There's a carb linq and sync procedure in the Yamaha Manual(You will need a manual). The idle speed is about 750RPM's, warm motor. You should prop for a wide open throttle of about 5500RPM's, give or take a couple of hundred. If your wide open throttle was say, 4500RPM's then your prop could be wrong and not good for motor. Maybe you can install a real tachometer which is very nice to have for future running efficiency. Good Luck!

 

[shackle101]

Re: 1993 85 hp C85TLRR yamaha Carb rebuild and prob question

Also the engine runs fine, but idles a bit rough and can be hard to start from sitting around for a day or so sometimes. At full speed it sounds perfect tho, when idling it has a small sputter sometimes.

 

[99yam40]

Re: 1993 85 hp C85TLRR yamaha Carb rebuild and prob question

I recommend the Yamaha service manual for your motor, not an after market one that covers many different years and models. But if you have never worked on a motor before I have no idea if you will get it done properly

 

[shackle101]

Re: 1993 85 hp C85TLRR yamaha Carb rebuild and prob question

I have experience with non marine motors. Rebuilt carbs on my dirt bike plenty of times. Yeah the Service manual is like $75 which is pretty insane, may have to bite the bullet. Also I've done all the general stuff on it before like foot oil, water pump replacement, and spark plugs but that's easier then carbs.

I found this one ebay: http://www.ebay.com/itm/1993-YAMAHA...anuals_Literature&vxp=mtr&hash=item46000fac11

Anyone used one of these before? I have my doubts.

I recommend the Yamaha service manual for your motor, not an after market one that covers many different years and models. But if you have never worked on a motor before I have no idea if you will get it done properly

 

[99yam40]

Re: 1993 85 hp C85TLRR yamaha Carb rebuild and prob question

look up the manual for your motor on the Yamaha site and then punch that # into your web search to see what you can find.
There are copy write laws on Yamaha pub. so who knows what you will get when ordering from others. you do that at your own risk

 

[shackle101]

Re: 1993 85 hp C85TLRR yamaha Carb rebuild and prob question

Just wanted to say thanks to everyone. Got the carbs rebuilt and the motor running great. (no leaks woot!). For others out there with this same engine it's pretty easy this is all you need to really know..

Needle Adjustments: As for the needle screws you just need to tighten to lightly snug (don't over tighten or you'll ruin the needle) and then loosen 1 1/8th turns out and it should be fine. If it won't stay running then your not doing a full turn correctly.

Throttle adjustment: loosen all screws for the throttle attachments on the carbs (on the top and lower carb and the throttle adjustment screw) and push the throttle lever all the way closed and tighten the screws up while holding the throttle lever down. Took me a few try's but if this isn't correct you won't get it under 900 rpms. The book recommends 800rpms for idle. Then after running for a couple mins just adjust the center carb throttle adjustment screw until you hit 800 rpms.

Also another tip: Spark plug gap is 0.9-1.0

These steps should be the same for 90-96 models.

Thanks

 

[robert graham]

Re: 1993 85 hp C85TLRR yamaha Carb rebuild and prob question

Glad you got it done and it's running fine, but I'm just curious, after opening up the carbs, were they really dirty and needing cleaning? Maybe it was just the carb jets that were partially plugged? Reason I ask, my motor is a 1999, 90HP, C model and I've never touched or cleaned the carbs, it's running just like a new one, but maybe someday they'll need cleaning? I do drain my carbs regularly.

 

[shackle101]

Re: 1993 85 hp C85TLRR yamaha Carb rebuild and prob question

I've seen carbs much dirtier, these where fairly clean. I put them in a ultra sonic cleaner tho just cause I already had them off. I had a minor leak which it seemed to repair also. I think the leak was caused by the stoppers attached to the floats. They had some minor ware. Honestly from what I've heard long as you maintain them well (drain and stabil) you'll won't need to replace for a long time. Also I think mine where running rough before due to the Fuel to air mixture screws being off a bit.