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Discussion Starter · #1 ·
Hey all,



I'm in the process of pulling the water pump cover to get to a bad engine speed sensor and have a quick question for those that have done this procedure before. It looks like I won't be able to access the final bolt holding the pump cover on (the topmost bolt) without pulling the air valve assembly out of the way. Am I correct in assuming this assembly will need to be removed to get the pump cover off? The factory manual gives this pretty light treatment, so thought I should check with the pros before potentially making a bunch of work for myself. Are there any tips or tricks to removing it - I've had a very good look around it and it's awfully tight in there.



Thanks for any info!



Sean
 

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Yes, but I'm doing this from memory, so let's see if I get it right (the 650T does not have the valve, only the 500T). it's easy. Just use needle nose pliers to loosen the pinch clamps holding the rubber hoses onto the valve. Then find the 8mm head bolts on top of the valve mounting plate that secures it to the engine, which I believe is partially rubber mounted like a motor mount, for shock (between the cylinders). It is a bit difficult to get to these, so remove the gas tank if you haven't already. Then you will need a 1/4" drive socket with a universal to connect to the 8mm socket. You have to start it with a box wrench, then loose with the socket and maybe even use the needle nose to back it all the way out; be patient, you'll get it. Remember while you have the housing out to change the mechanical seal (you can use a Yamaha seal, it's about 1/2 the price of the Honda unit and usually in stock at the dealer). Also, make sure you get the polarity correct on your sensors, if you are rebuilding yours. I would recommend installing it into the housing, but NOT final solder you wiring until you know they are correct, then mate it up to the harness plug. There has been lot's of discussion over the sensors and polarity. Overall, an easy and effective fix, just a bit time consuming. Remember; YOU CAN DO THIS.....all the help you need is one simple forum entry away..............
 

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Discussion Starter · #3 ·
HomerRod -



Thanks for the clarification and the tips. I'm always impressed by the knowledge base and the guidance available in the forum! New speed sensor and the Yamaha seal are on order...
 

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Yes, HomerRod is correct!



Also, be VERY careful when removing the impeller as a lot of people have broken their camshafts prying it off.
 

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Discussion Starter · #5 ·
Thanks for the heads up ishootstuff....





Which brings me to where I am currently:



Picked up a replacement speed sensor, and the Yamaha mechanical seal. Air valve, pump cover, impeller retaining nut/washer, throttle housing bracket (8mm) removed successfully.



I'm now at the point of removing the impeller, and then the pump body.



Breaking the camshaft would really ruin my day. Does anyone have any tricks for easing the impeller off the shaft, and then removing the pump body while minimizing the risk to the camshaft?



There's some rust evident in the impeller housing, so it looks like corrosion has set in at some point - I've been soaking it with penetrating fluid before trying much more to remove it - but thought I'd check in here before proceeding.



Also - I presume the mechanical seal driver is unobtainable, or even likely not required to install the mechanical seal - can someone confirm, or recommend a suitable replacement for the driver?



Thanks for all of the help and guidance!
 

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I've used two large flat blade screw drivers to gently pry off the impeller. Equal force on each side of the impeller is important. They came off easily on both my bikes that way.

The pain in the ass is the sensor lobe which needs to be removed if you're doing a stator replacement. It tends to fuse itself to the camshaft. I found a special puller at Autozone that works great. If all you're doing is the mech seal you won't need to remove that lobe.



You don't need anything special to install the new mech seal. Punch out the old one and tap in the new one with an appropriate sized deep well socket. I think it was a 12 point 1" socket that works perfect.



When reassembling make sure the impeller is fully seated. The torque spec for that acorn nut is very little and may not be enough to seat the impeller if it hangs up. I had that happen on my 650 which leaked after starting it up. Had to pull the cover again and retorque that nut.

Of course use a new copper washer is a must and some mild locktite on the nut wouldn't hurt.
 

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I've used two large flat blade screw drivers to gently pry off the impeller. Equal force on each side of the impeller is important. They came off easily on both my bikes that way.

The pain in the ass is the sensor lobe which needs to be removed if you're doing a stator replacement. It tends to fuse itself to the camshaft. I found a special puller at Autozone that works great. If all you're doing is the mech seal you won't need to remove that lobe.



You don't need anything special to install the new mech seal. Punch out the old one and tap in the new one with an appropriate sized deep well socket. I think it was a 12 point 1" socket that works perfect.



When reassembling make sure the impeller is fully seated. The torque spec for that acorn nut is very little and may not be enough to seat the impeller if it hangs up. I had that happen on my 650 which leaked after starting it up. Had to pull the cover again and retorque that nut.

Of course use a new copper washer is a must and some mild locktite on the nut wouldn't hurt.


George, of course, is absolutely correct. Breaking a cam would really suck. It's like everything else on these bikes; take your time and be patient. There are lots of screws,nuts and bolts that have not been removed in 27 years. They will need some gentle coaxing. The two equally applied screwdrivers is a great idea, especially considering the cam is cast iron unit with the impeller threads being a very narrow area, and is more prone to breakage. Locktite on the acorn nut is good; I've done that before. The Yamaha seal has never failed me; I've used them three times. Sounds like you've just about got it nailed down.......good job!!
 

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Discussion Starter · #8 ·
Wanted to provide an update to this post for the benefit of those who were kind enough to offer advice (and for those who may someday tackle this same issue).



After a few delays (life got busy), I managed to get back to this and finish it up. I used the large flat blade screwdriver method to evenly pry the impeller loose (hung up due to corrosion) and then the pump body. In the end, I decide to replace both speed sensors while I was in there (sourced one on ebay, and one through rockauto.com) even though one was still within specifications. Spent a lot of time cleaning up all of the corrosion that had set in (due to a mechanical seal that had long since failed....and clogged the weep hole with corrosion so that the leak was not apparent). The Yamaha seal went in with no major issues (used a large socket as the driver), and I was extra careful with respect to the polarity of the sensors (took lots of pictures during disassembly). I ended up using the red-to-striped wire system outlined in Pim's writeup elsewhere on this site. New impeller cap nut washer, o-rings and pump cover seal and all went back together smoothly. Got it all buttoned back up, and bike fired up immediately and settled into a even idle (no fuel system warning light!!!). Just got back from a 35 mile test ride, and it ran great, fueled properly, and still shows no warning lights! I've declared the operation a success, and needless to say, I'm ecstatic to have the Turbo back.



Thanks to all those who helped me out, and to all those who share their knowledge on this board - it's an invaluable resource to those of us trying to keep these bikes on the road!
 

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Wanted to provide an update to this post for the benefit of those who were kind enough to offer advice (and for those who may someday tackle this same issue).



After a few delays (life got busy), I managed to get back to this and finish it up. I used the large flat blade screwdriver method to evenly pry the impeller loose (hung up due to corrosion) and then the pump body. In the end, I decide to replace both speed sensors while I was in there (sourced one on ebay, and one through rockauto.com) even though one was still within specifications. Spent a lot of time cleaning up all of the corrosion that had set in (due to a mechanical seal that had long since failed....and clogged the weep hole with corrosion so that the leak was not apparent). The Yamaha seal went in with no major issues (used a large socket as the driver), and I was extra careful with respect to the polarity of the sensors (took lots of pictures during disassembly). I ended up using the red-to-striped wire system outlined in Pim's writeup elsewhere on this site. New impeller cap nut washer, o-rings and pump cover seal and all went back together smoothly. Got it all buttoned back up, and bike fired up immediately and settled into a even idle (no fuel system warning light!!!). Just got back from a 35 mile test ride, and it ran great, fueled properly, and still shows no warning lights! I've declared the operation a success, and needless to say, I'm ecstatic to have the Turbo back.



Thanks to all those who helped me out, and to all those who share their knowledge on this board - it's an invaluable resource to those of us trying to keep these bikes on the road!




Glad to hear it worked out. I had no doubt that you would get it; being patient and allowing lots of time is almost a necessity for these bikes. This forum has proved invaluable for both the new owners and the veterans (and yest, I get stumped every once in while!!). Collectively, there is just about no problem that we cannot or have not solved. Enough said:

NOW GO ENJOY THE FEEL THAT ONLY OUR TURBO'S CAN PROVIDE !!!!
 
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