1974 Kawasaki F7 175 Info Please... - Page 2

Shocktower · 02-20-2012, 03:27 AM

Hey ya know what would help some of the n00bs is you guy's post some of this info here

Euromad · 02-20-2012, 06:29 AM

I have a donor '74 175 and a running '73 175. What do you want to know?
Here's a brief overview:
-Kawasakis were the main user of the rotary valve engine of the Japanese bikes but CanAm's used them with great success.
-My Clymer lists 80-350cc models from '66 t0 '94

-The rotary valve opens to allow the fuel mix into the crank cavity and then closes until the down stroke is complete. Thios keeps the charge in the crank instead of spitting back through the carb.
For early two strokes this was a great way to broaden the powerband. The exhaust pipes didn't use the exhaust pulses to scavenge the spent exhaust very well. If you look at a modern two stroke pipe it is fat and thin in different areas to make the best use of this exhaust pulsing to suck the spent gases out of the cylinder.

Yamaha used reed valves for a similar effect. The flexible reed opens when the engine sucks in the fuel mixture and closes when the exhaust back pressure pushes back. It's located in between the carb and cylinder.
The reed valve works best for increasing the low end power and becomes useless at higher rpms as it stays open.
The main disadvantages of the rotary valve are complexity, and increased case width.

lake_harley · 02-20-2012, 04:30 PM

Quote:

Originally Posted by Euromad

Thios keeps the charge in the crank instead of spitting back through the carb.
For early two strokes this was a great way to broaden the powerband. The exhaust pipes didn't use the exhaust pulses to scavenge the spent exhaust very well. If you look at a modern two stroke pipe it is fat and thin in different areas to make the best use of this exhaust pulsing to suck the spent gases out of the cylinder.

Would it then be inaccurate to think that a rotary valve engine (F7) wouldn't benefit as much from a "performance" expansion chamber as a reed valve or port timed engine? I want to build a low mount expansion chamber for my "street tracker" 175 instead of the high mount stock pipe, but really don't know the first thing about expansion chamber design. I wouldn't want to build something that looked pleasing but it actually hurt performance/power. Then again, I'm not looking to squeeze the last bit of power from the otherwise stock, almost 40 year old engine either.

Lynn

JeffS77 · 02-20-2012, 06:29 PM

expansion pipes are still needed on rotary valve motors to make peak power.

something to check out

klemmvintage.com

and check out the Big Horn 350 road racers they build

http://www.klemmvintage.com/bighorntech.htm

Kelly_O · 02-20-2012, 08:27 PM

Oh, I get it. Jeff the Instigator! How the hell am I going to keep Tracy happy with her stock exhaust if she knows there are expansion chambers for her F7?

Euromad · 02-21-2012, 06:00 AM

What Jeff said. If you have the skills a period pipe from another bike could be modified or you can build one. I'm going to take the stock head pipe and weld it to a period high pipe myself . I'd post pics but apparently I'm not old enough on this site.

Kelly_O · 02-25-2012, 03:55 PM

Well Fellers, We took delivery of the '74 F7 last night. It's got years of built-up oil and dirt on it. Tracy and I spent an hour or so cleaning it up. I'd say we're 15% done with the cleaning. We only concentrated on the engine area and front forks. It'll need fork seals. It appears to have the factory front fender, but someone took the "brace" off of it. If anyone has one they'd like to sell, I'm all ears. I also bought a tail light for it from Ebay. I wasn't wanting to pay $33 for a new lens and another $8 for a gasket. The 75 KZ400 tail light assembly from Ebay shares the part numbers with the original, and cost me $19.99 shipped.

The Clymer's manual should be here in a few days. I'll keep you posted, Kelly.

Euromad · 02-26-2012, 02:25 PM

I have a front fender with the brace- the fender is a little banged up but complete. Also have the stock tailight and rear fender and some other odds and ends.
I've been stripping one down and building up another. We'll have to compare notes

Kelly_O · 03-04-2012, 09:00 PM

Hey F7 Gods, It appears as though there should be a hose starting at the top of the oil tank and.... That's the question. Where does it go from there?
Oh, and back to the battery. Will running the bike with a dead battery hurt anything? I say no, but would like your opinion. Thanks, Kelly.

P.S. Tracy's F7...

SprintSix · 03-05-2012, 03:08 AM

Yes, your ok without a battery. I think the headlight has direct power from the generator.

You will change the bike from mild to wild with an expansion chamber. Torgue Engineering, Whisperin' Smith. Also Hooker and Bassani made pipes for them.

The shocks are a major weak point, they like to kick hard . Spend as much as you can there.

Clutch is another weak point. Barnett sells a good kit. If yuo use an expansion chamber you will need this

If your in the forks anyways... Gold valves are worth it.

Keep the injection.

lake_harley · 03-05-2012, 05:19 AM

Quote:

Originally Posted by Kelly_O

Hey F7 Gods, It appears as though there should be a hose starting at the top of the oil tank and.... That's the question. Where does it go from there?

The tube attachment point at the top of the injection oil tank, just on the inside of the frame tube is a vent. On mine, and I don't know if it's routed properly, it just goes back and down to an area near the swingarm pivot like the other vent tubes.

On the battery question, I've read running without the battery will fry the ignition or something so I elected to not take that chance on mine.

Lynn

Kelly_O · 03-05-2012, 10:28 AM

Thanks guys, I'm going by what I've read, and learning as I go. You fellas are invaluable as a resource. Thanks, Kelly.

Kelly_O · 03-05-2012, 05:19 PM

The F7 lives! The nice temps (50ish) made us do it. I bought some fuel for the F7 and my TT600. When Tracy got home from work this afternoon she wanted to start HER bike. I put some gas in it, checked the air filter for rodent condos, and gave her the OK to try. About 6 kicks and we had smoke.
We also have a carb problem. I'm guessing needle and seat trouble. With the choke on it starts right up and goes to about 4k rpms. It runs for a few seconds and tries to die. If I shake the bike hither and yon it will rev back up to where it was. Then it repeats that behavior. I think we could do this all day long. You get the picture. What say you? Thanks for your continued support, Kelly.

Euromad · 03-12-2012, 04:21 PM

My thoughts are to clean the carb, lube the throttle cable and check for air leaks. The rotary valve setup has a lot of potential air leaks- the side cover, theboot, and the cables going into the case. If it doesn't idle down the slide or the cable could be sticking.

Kelly_O · 03-12-2012, 08:02 PM

Quote:

Originally Posted by Euromad

My thoughts are to clean the carb, lube the throttle cable and check for air leaks. The rotary valve setup has a lot of potential air leaks- the side cover, theboot, and the cables going into the case. If it doesn't idle down the slide or the cable could be sticking.

The Wife (Tracy) pulled the carb yesterday and gave it a good going-over. It runs fine now. It was Tracy's first carb job. Photo proof...

02-20-2012, 03:27 AM	#16
Shocktower Beastly Adventurer Joined: Jul 2009 Location: Oregon City Orygun Oddometer: 8,234	Hey ya know what would help some of the n00bs is you guy's post some of this info here __________________ Alexa Drew Nov 9 1995- Oct 28th 2004 Miss you baby '08 KTM 530 EXC 79 RD 400 Daytona

02-20-2012, 06:29 PM	#19
JeffS77 cheap bastard Joined: Apr 2006 Location: Riverside , CA Oddometer: 2,998	expansion pipes are still needed on rotary valve motors to make peak power. something to check out klemmvintage.com and check out the Big Horn 350 road racers they build http://www.klemmvintage.com/bighorntech.htm __________________ A n00b Races Hell on Wheels Vintage Scrambles A n00b Races Elsinore Grand Prix For a Cause A n00b Goes Flat Track Racing JeffS77 screwed with this post 02-20-2012 at 09:07 PM

03-04-2012, 09:00 PM	#24
Kelly_O ^OP Gnarly Adventurer Joined: Jul 2010 Location: Rifle, Colorado Oddometer: 301	F7 Info Part Dos... Hey F7 Gods, It appears as though there should be a hose starting at the top of the oil tank and.... That's the question. Where does it go from there? Oh, and back to the battery. Will running the bike with a dead battery hurt anything? I say no, but would like your opinion. Thanks, Kelly. P.S. Tracy's F7...

03-05-2012, 05:19 PM	#28
Kelly_O ^OP Gnarly Adventurer Joined: Jul 2010 Location: Rifle, Colorado Oddometer: 301	It is ALIVE! The F7 lives! The nice temps (50ish) made us do it. I bought some fuel for the F7 and my TT600. When Tracy got home from work this afternoon she wanted to start HER bike. I put some gas in it, checked the air filter for rodent condos, and gave her the OK to try. About 6 kicks and we had smoke. We also have a carb problem. I'm guessing needle and seat trouble. With the choke on it starts right up and goes to about 4k rpms. It runs for a few seconds and tries to die. If I shake the bike hither and yon it will rev back up to where it was. Then it repeats that behavior. I think we could do this all day long. You get the picture. What say you? Thanks for your continued support, Kelly.

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02-20-2012, 06:29 AM	#17
Euromad Gnarly Adventurer Joined: Feb 2010 Location: Lower Slobbovia Oddometer: 154	I have a donor '74 175 and a running '73 175. What do you want to know? Here's a brief overview: -Kawasakis were the main user of the rotary valve engine of the Japanese bikes but CanAm's used them with great success. -My Clymer lists 80-350cc models from '66 t0 '94 -The rotary valve opens to allow the fuel mix into the crank cavity and then closes until the down stroke is complete. Thios keeps the charge in the crank instead of spitting back through the carb. For early two strokes this was a great way to broaden the powerband. The exhaust pipes didn't use the exhaust pulses to scavenge the spent exhaust very well. If you look at a modern two stroke pipe it is fat and thin in different areas to make the best use of this exhaust pulsing to suck the spent gases out of the cylinder. Yamaha used reed valves for a similar effect. The flexible reed opens when the engine sucks in the fuel mixture and closes when the exhaust back pressure pushes back. It's located in between the carb and cylinder. The reed valve works best for increasing the low end power and becomes useless at higher rpms as it stays open. The main disadvantages of the rotary valve are complexity, and increased case width.

02-20-2012, 08:27 PM	#20
Kelly_O ^OP Gnarly Adventurer Joined: Jul 2010 Location: Rifle, Colorado Oddometer: 301	Oh, I get it. Jeff the Instigator! How the hell am I going to keep Tracy happy with her stock exhaust if she knows there are expansion chambers for her F7?

02-21-2012, 06:00 AM	#21
Euromad Gnarly Adventurer Joined: Feb 2010 Location: Lower Slobbovia Oddometer: 154	What Jeff said. If you have the skills a period pipe from another bike could be modified or you can build one. I'm going to take the stock head pipe and weld it to a period high pipe myself . I'd post pics but apparently I'm not old enough on this site.

02-25-2012, 03:55 PM	#22
Kelly_O ^OP Gnarly Adventurer Joined: Jul 2010 Location: Rifle, Colorado Oddometer: 301	Well Fellers, We took delivery of the '74 F7 last night. It's got years of built-up oil and dirt on it. Tracy and I spent an hour or so cleaning it up. I'd say we're 15% done with the cleaning. We only concentrated on the engine area and front forks. It'll need fork seals. It appears to have the factory front fender, but someone took the "brace" off of it. If anyone has one they'd like to sell, I'm all ears. I also bought a tail light for it from Ebay. I wasn't wanting to pay $33 for a new lens and another $8 for a gasket. The 75 KZ400 tail light assembly from Ebay shares the part numbers with the original, and cost me $19.99 shipped. The Clymer's manual should be here in a few days. I'll keep you posted, Kelly.

02-26-2012, 02:25 PM	#23
Euromad Gnarly Adventurer Joined: Feb 2010 Location: Lower Slobbovia Oddometer: 154	I have a front fender with the brace- the fender is a little banged up but complete. Also have the stock tailight and rear fender and some other odds and ends. I've been stripping one down and building up another. We'll have to compare notes

03-05-2012, 03:08 AM	#25
SprintSix Gnarly Adventurer Joined: Dec 2009 Location: Ohio Oddometer: 132	Yes, your ok without a battery. I think the headlight has direct power from the generator. You will change the bike from mild to wild with an expansion chamber. Torgue Engineering, Whisperin' Smith. Also Hooker and Bassani made pipes for them. The shocks are a major weak point, they like to kick hard . Spend as much as you can there. Clutch is another weak point. Barnett sells a good kit. If yuo use an expansion chamber you will need this If your in the forks anyways... Gold valves are worth it. Keep the injection.

03-05-2012, 10:28 AM	#27
Kelly_O ^OP Gnarly Adventurer Joined: Jul 2010 Location: Rifle, Colorado Oddometer: 301	Thanks guys, I'm going by what I've read, and learning as I go. You fellas are invaluable as a resource. Thanks, Kelly.

03-12-2012, 04:21 PM	#29
Euromad Gnarly Adventurer Joined: Feb 2010 Location: Lower Slobbovia Oddometer: 154	My thoughts are to clean the carb, lube the throttle cable and check for air leaks. The rotary valve setup has a lot of potential air leaks- the side cover, theboot, and the cables going into the case. If it doesn't idle down the slide or the cable could be sticking.