1985 Shadow 700 gutless

[dvldogg187]

I want to start by thanking everyone for all of your previous posts and would like to thank all the knowledgeable people who have helped others with their questions.

I recently purchased a 1985 Shadow 700 with 40k miles on it. Using the shop manual and the advice of the people who have posted here I have done a good deal of basic overall maintaining to the bike.

I ran 2 bottles of seafoam through it.
I pulled every plug and connection apart and cleaned them up.
Changed coolant.
Changed oil.
Rebuilt tach....(thanks for the great info on that)
Cleaned all switches and relays.
New plugs.
Cleaned air filter.
New tires.
Measured all impedences in the ignition system per shop manual (all is well)
Charging system works great (soldered up those 3 yellow wires just in case).
Checked the boots on the intake.

The problem is when i get on it, it seems to do just fine, but I can't get the darn thing to go over 75. 50 - 65 seems to have a lot of get up and go, but after that it just seems to fall off. There is no stumbling of the motor. The clutch isn't slipping, there just isn't anything there. I'm pulling ~4000 RPMs at 65 mph.

Going uphill makes it gutless, and forget trying to pass anyone.

I've read some posts on damage to the diaphragm causing a loss of power at higher speeds but I haven't gotten that far into the motor yet.

This is the first motorcycle I've owned so I don't know how much power it's supposed to have but I read some posts that some people wrote saying it should be able to do ~100 mph.

When it's in neutral and I give it throttle up to 3 or 4 k RPMs after I let off on the throttle it kinda hangs there for a second and then revs down, is this a mixture issue?

I was thinking maybe it's because I'm 6'3" 280, I kinda make a big sail, and I might throw the power to weight ratio off a little bit. Could this be the problem, is the bike to small for me? Or am I missing something.

Any advice you guys have will be greatly appreciated. The thing runs like a champ, doesn't miss or backfire (a little blub blub blub on deceleration somethings but nothing I would think would be abnormal) I can't understand why it has a huge flat spot after 75.

[SHADOW 1100T]

If there is a crack in the carb diaphragm it will fall off at the upper speeds because the diaphragm can't lift the slide anymore, just pull the top off the carb and pull it out, hold it to a bright light and really take a close look moveing it around and flexing it. if you have to replace it don't expect any great big gains, it is a 700 and there's only so much HP it can produce but it should be better, probably in the 90's.

[Easy Rider 2]

Originally Posted by dvldogg187

I was thinking maybe it's because I'm 6'3" 280, I kinda make a big sail, and I might throw the power to weight ratio off a little bit. Could this be the problem, is the bike to small for me? Or am I missing something.

I think you've got it scoped out pretty good. The "big sail" is more a factor than the weight.

I'm a good bit smaller than you; I have an '07 600. I expect it is roughly equivalent to your 20+ year old 700. Like you, I can get TO 70 with no problem but after that it starts to run out of HP. I'm pretty sure I could nurse it to around 90 but it would take a while. I have a windshield which no doubt helps some.

So, yes, IMHO if you need to go over 75 very often, you need to shop for a slightly bigger engine. I doubt that there is really anything "wrong" with your present ride......except that it is just old.

[sunnyrider]

Actually, the 85 VT700C has, when running correctly, about 65hp and the 07 600, when running correctly, has about 40hp. So your 85 should have quite a bit more giddy-up. You definitely have a problem, I just can't help you with what. But my 84 has absolutely no problem hauling my fat fanny well above 85mph...chicken factor kicks in brings the speed back to sane levels.

[Easy Rider 2]

Originally Posted by sunnyrider

Actually, the 85 VT700C has, when running correctly, about 65hp and the 07 600, when running correctly, has about 40hp. So your 85 should have quite a bit more giddy-up.

WOW. Good information.

A higher HP rating usually goes along with a higher RPM/red line rating.
I wonder if the final drive has been changed (if it is a chain)?

That extra HP won't be there if you can't achieve the engine speed necessary to develop it. Maybe just rev'ing it a bit higher in the next-to-last gear would help some.

Do you have the engine speeds where those ratings are measured......like 65hp@7000 rpm...... ??

[sunnyrider]

Originally Posted by Easy Rider 2

WOW. Good information.

A higher HP rating usually goes along with a higher RPM/red line rating.
I wonder if the final drive has been changed (if it is a chain)?

That extra HP won't be there if you can't achieve the engine speed necessary to develop it. Maybe just rev'ing it a bit higher in the next-to-last gear would help some.

Do you have the engine speeds where those ratings are measured......like 65hp@7000 rpm...... ??

The 1985 has a shaft drive.

1985 VT700C = 63hp@7500rpm
2007 600 = 39hp@6500rpm

[dvldogg187]

Originally Posted by Easy Rider 2

WOW. Good information.

A higher HP rating usually goes along with a higher RPM/red line rating.
I wonder if the final drive has been changed (if it is a chain)?

That extra HP won't be there if you can't achieve the engine speed necessary to develop it. Maybe just rev'ing it a bit higher in the next-to-last gear would help some.

Do you have the engine speeds where those ratings are measured......like 65hp@7000 rpm...... ??

I haven't really opened it up to 7000 rpms. I'll do 5500 to 6000 sometimes but I try to be a bit more conservative with it, it is a 24 year old motor with 40k miles on it.

Gonna take the tank off and look at the diaphragms this afternoon. Is it possible to repair them with rubber cement or finger nail polish or anything like that? Duck Tape?

[83_Shadow_750]

Yah you've got something going on. My 83 750 will hit 90 MPH quick, but that's as fast as I've had it. There's more there. It redlines @ 8000. I weigh about 200.

[SHADOW 1100T]

Is it possible to repair them with rubber cement or finger nail polish or anything like that? Duck Tape?
======================================
NO,,,But you an get a temp fix useing the sticky part of a "Sheer" Band Aid, the plastic is very thin and will flex with the diaphragm and is sticky as heck,,, but it's a temp fix.

[landon]

I have an 84 VT700C, my book says that the 84 and 85 are both rated for 62 BHP @ 7500 rpms.

I weigh about 200 and even with a full tank of gas, both saddle bags full, stuff on the back rack and wearing a back pack she still has no problems getting up to 80mph and flies up hills with no problems. You are only 80 pounds heavier than me which is probably about the weight of all the crap I carry so we should be about even on the weight distribution.

As far as not knowing how much power it should have on an average temperate day it should feel like it has enough power to really make itself move, on a good hot dry day with the temp over 70 degrees it will really wake you up when you gun it, you will feel the extra power being made.

At least that is how mine runs.