1990 intruder 750

[Mrparks88]

Hey everyone. I'm helping a friend with his new 1990 750 and we found the radiator is boiling after a ride. I intend to check and make sure it doesn't need flushed again already but last time I noticed the cap wasn't in the nest condition. Does anyone know of a direct fit from any car? Thanks in advance. Also I can't get the search function here to work on my phone

[Lechy]

Like Keith said, E-Bay. Make sure you get the correct rated pressure, it should be stamped on the cap. Down side may be that like my recently resurrected 750, started boiling over after about 200 miles, then the oil disappeared from the sight glass after a 50 mile hard ride. I checked the water and it looked like mud. I have the engine out and on the bench partially stripped down whilst waiting for a new gasket set.
Ah, the joy's of motorsickles, especially old ones.
[emoji41]

[Mrparks88]

She boiled a little last night but I'm pretty sure the heads are safe. We didn't consider burping ut before we rode her so she was a little low and full of air hence the boiling. And I'm gonna try to parts match at autozone or the like. I just wasn't sure if anyone already had and knew a number.

[Mrparks88]

Like Keith said, E-Bay. Make sure you get the correct rated pressure, it should be stamped on the cap. Down side may be that like my recently resurrected 750, started boiling over after about 200 miles, then the oil disappeared from the sight glass after a 50 mile hard ride. I checked the water and it looked like mud. I have the engine out and on the bench partially stripped down whilst waiting for a new gasket set.
Ah, the joy's of motorsickles, especially old ones.
[emoji41]

Are these engines hard to remove?

[Mrparks88]

Also. Anyone know a thermostat for these?

[Lechy]

Any kind of work on these bikes is a real ball-ache, especially if you have fat fingers. Getting the engine out isn't very difficult if you have a small 1 ton trolley jack and can think outside of the box a little to get the machine high and secured enough. Pulling the jugs is quite easy (ha ha ha) once you have the water couplings between the jugs removed, I learned a whole new language of cuss words doing that little job. But, hopefully you won't have to resort to that. If the oil in the sump is black and the water is clear or green (antifreeze/corrosion inhibitor) I wouldn't be worrying too much. All parts are available on E-Bay, just do a search for Intruder 750 xxxxxxxx.

[emoji41]

[Mrparks88]

The oil was insanely black. Antifreeze was brown. Rusty and foamy. No oil though. It sat for a few years. Can I run it without a thermostat?

[Lechy]

Depends on the ambient temperature, if it is warm where you live the engine will warm up no problem, but if you live in Alaska, it will take freakin' ages to get to operating temp. The idea of a 'stat is to stop the water flowing through the radiator until it has reached an optimal temp for the engine to perform at its best.
[emoji41]

[SoakedKarma]

Can I run it without a thermostat?

No! not advised
thermostat acts as a flow restriction.. Removal can cause coolant to pass too quickly through radiator and not be cooled efficiently.. may result in boil over condition. may not.

Workaround is to get thermostat to open by dunking in boiling water and/or physical force and solder tin strip across supports to hold valve open.. thus providing proper coolant flow restriction.. Takes longer for the engine to warm up though.........

[Mrparks88]

So basically lock it open. Is there a way too ensure it does in fact operate as needed without taking it out? I don't have a spare gasket And I think it would be difficult to remove. Haven't looked that closely yet.

[Lechy]

Can I run it without a thermostat?

No! not advised
thermostat acts as a flow restriction.. Removal can cause coolant to pass too quickly through radiator and not be cooled efficiently.. may result in boil over condition. may not.

Workaround is to get thermostat to open by dunking in boiling water and/or physical force and solder tin strip across supports to hold valve open.. thus providing proper coolant flow restriction.. Takes longer for the engine to warm up though.........

Bad advice, you may just as well remove it and throw it away. Stats are cheap, replace it if you are not sure. Running without one will not allow the engine to get to operating temp in a timely manner causing the engine to stay cool for an extended period of time, like I said, if the ambient temp is high, operating temp will be reached in a timely manner, if it is cold, the engine will stay cold longer , fuel consumption will rise and lubrication will not be as effective. Any experienced rider or driver knows that you always take it easy on the throttle until the engine temp is up to operational levels. As for gaskets, get some gasket material and you can make your own or buy OEM which are cheap enough. As for boil over, that will happen if your fan switch is not working and you are in a hot environment and in slow moving traffic or you still have air in the system which will not be boil over but gas expansion. It is very rare for the fan to operate on these bikes in normal riding conditions. Stats are designed to fail in the fully opened position so if your bike is taking longer than normal to warm up it may need replacing, if it is over heating, you have a different problem.

[emoji41]

[Mrparks88]

The fan did come on but it did not overheat. I heard boiling but that again could be air. I'll use the gasket sealer. If it stays open when it fails then I'll double check it for now, ensure its actually there and order one. He plans on riding it Saturday. I'll make sure it's good. Think he'd be safe to ride for a couple days until the new one gets there?

[Mrparks88]

And no she warms up about like my other water cooled. No issues.

[enforcer]

Like Lechy stated, thermostats are meant to fail open. In a car, like a modern one, all that means is you just don't get any heat, due to over cooling. I know, I've had it happen. And like he stared, the motor never properly reaches temp. With fuel injection, no big deal. Carburetor, I wouldn't run it to too long that way. The point of a choke or enricher like we have is to add fuel until the bike is warm. If it never reaches that temp, you continue wasting fuel and never being able to successfully burn off all the carbon deposits. That's not good for your motor.

[Mrparks88]

I bit the bullet and tore her apart. Water Pump liked almost brand new. I tested the thermostat ands she operates perfectly. But a plastic impeller? Cmon suzuki..

[enforcer]

I bit the bullet and tore her apart. Water Pump liked almost brand new. I tested the thermostat ands she operates perfectly. But a plastic impeller? Cmon suzuki..

Common issue. That's the reason for bars leak in the coolant. Lubricates the water pump. Also takes silicate free coolant.