'79 GS1000S - 1085 Wiseco Kit - overheats at low speeds

[Nessism]

I disagree that a series R/R effects oil temp beyond some minimal amount. The only way for the stator to increase oil temp is if the stator itself is hotter than the oil AND coming into contact with the oil. For one thing, the stator only gets minimal splash oil flow. The volume of oil hitting the stator could not possibly heat the entire sump. And in order for the stator to heat the oil at all it would have to be scorching hot. How can this happen when only about 50W of power is getting shorted back to the stator during high rpm riding?

I also disagree that an engine with a big bore kit will automatically run noticeably hotter than a stock engine while cruising. The power demands to push the bike at any given speed are dictated by friction (rolling and internal) and wind drag. It's not like a big bore engine makes more power all the time. It only makes more power when the pilot twists the throttle.

 

[chuck hahn]

I would think the larger displacement would require larger jets as well to effect as perfect a performing engine as possible. To not rejet would also be a reason for it going lean and overheating...yes????

 

[IanR]

Adding an 1150 oil cooler (and filter cover) to my stock 1075, dropped temps so much I usually ride with the cooler covered up with cardboard. It still runs much cooler than it did before.

If your jetting is correct, sounds like you need an oil cooler. Doesn't a big-bore make more heat?

Rob, I'd be grateful if you could show me what the oil cooler arrangement is on your bike. I see that for the 1150s the oil lines appear to come off the oil filter cap, which look like they use the same 3 stud arrangement as on my GS1000S. I'd prefer this method to replacing the oil pressure switch plate and bringing the oil lines from behind the engine.

 

[Nessism]

Rob, I'd be grateful if you could show me what the oil cooler arrangement is on your bike. I see that for the 1150s the oil lines appear to come off the oil filter cap, which look like they use the same 3 stud arrangement as on my GS1000S. I'd prefer this method to replacing the oil pressure switch plate and bringing the oil lines from behind the engine.

The 16V 1100 engine has a different oiling system. For the 8V engines the adapter plate is the proper method.

 

[posplayr]

I run a RR off a Goldwing, sh775, it also sits out in the air just above the swingarm on my 1085. It definitely helped with the temps, as you stated.

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[posplayr]

The 16V 1100 engine has a different oiling system. For the 8V engines the adapter plate is the proper method.

As Ed said

 

[Guest]

OK that is a good explanation (even using Bernoulli) but how does it predict a better flowing head needs smaller main jets? Do we need a composite theory?

I never said that better flowing heads need smaller main jets; usually the contrary, unless your 'flow job' didn't do what you'd hoped. Somebody else said that about automotive carbs; I never found that to be the case, but I only work on cars when they're broken?.

There are those who increase the size of the hole and expect that more will magically flow through it. It's far more complex than that.

 

[posplayr]

I never said that better flowing heads need smaller main jets; usually the contrary,

No I don't think you ever said it but it is fact. So my comment relative to jetting is because to be satisfactory it would need to explain the three elements I mentioned, not just #1

1. Increase bored (compression) required increased jetting
2. Improved head flow reduces jetting
3. Increased cams requires increased jetting.

I added compression to #1 because all the street BB kits bump up compression. Again items #1 thru #3 are established fact at least for the 16V 1100's. I'm sure Ray or Blower can corroborate that as well.

 

[Fjbj40]

I do pay attention to what the senior guys on this forum have to say! I read many posts by you Posplayr, the SH775 advice, SPG, coil relay mods, starter clutch kill switch mod plus many more.

I also used SaltyMonk, Blowerbike, Chef, Rapidray and Tone and many others advice on many things.

People just need to search and read lots, pretty much every problem, mod and repairs are on this forum, just got to SEARCH!

Cheers,
Daryl

 

[Guest]

Any increase to the surface area of the engine internals will pull more quantity of heat from the process than a lesser area. That's why Subaru, for example, has gone to a smaller bore longer stroke engine recently. Big bore, short stroke engines are less thermally efficient - lose more heat to the head and barrel - than small bore long stroke, because the process is mostly over by the time the rest of the bore is exposed. Subaru had a hard time being competitive on mileage - thermal efficiency - until they went from a rather over square 92 X 67 down to 77 X 83 or whatever it went to.

The increase in surface area will be the square of the difference in diameter.

The thickness of the barrel acts like a flywheel, storing heat and minimizing fluctuations, but the external surface area determines the eventual temperature. In this case, the internal surface has been increased but the outer surface remained the same. Even at the same speed it should run a bit hotter.

 

[posplayr]

The thickness of the barrel acts like a flywheel, storing heat and minimizing fluctuations, but the external surface area determines the eventual temperature. In this case, the internal surface has been increased but the outer surface remained the same. Even at the same speed it should run a bit hotter.

By external area, you mean the external engine surface area (e.g. fin area) of the engine to convect heat away?

 

[rapidray]

Did you guys even READ my post? Again I will tell you the cause of the heat:

COMPRESSION!!!!

Ray.

 

[posplayr]

Did you guys even READ my post? Again I will tell you the cause of the heat:

COMPRESSION!!!!

Ray.

Yea but why does it need to be jetter richer?

 

[IanR]

Ok. Thanks for letting me know.

 

[posplayr]

Ok. Thanks for letting me know.

Please report back on the findings; you can add to the database

 

[60ratrod]

rejetting to be richer in theory should help to cool off due to the increased compression and the slight cooling effect of the additional fuel entering the cylinder. also, depending on how much you increase the compression ratio, you may need to run higher octane fuels. lower octane fuels to not burn efficiently enough and can cause pings, knocks, and detonations, things that can destroy all that you have done. also, there has been some research done showing that running higher octanes can help cool internal temps, since lower octane fuels burn faster, keeping the heat trapped in the head and cylinder longer and potentially causing the pings, knocks and detonations. it may be worth running a tank or two to find out.

i don't know how true this is to our small displacement engines compared to car small/big block v8 engines, but in say a small block chevy, the maximum compression ratio for regular 85, or your region's equivalant lowest octane rating is, is about 9.5:1 which is about 190psi +/- 10psi per cylinder. i know that the stock compression ratio is 8.5:1 or 150psi for both my suzuki gs650g and my kawasaki kz1000m1, allowing for lower octain fuels.

 

[posplayr]

rejetting to be richer in theory should help to cool off due to the increased compression and the slight cooling effect of the additional fuel entering the cylinder. also, depending on how much you increase the compression ratio, you may need to run higher octane fuels. lower octane fuels to not burn efficiently enough and can cause pings, knocks, and detonations, things that can destroy all that you have done. also, there has been some research done showing that running higher octanes can help cool internal temps, since lower octane fuels burn faster, keeping the heat trapped in the head and cylinder longer and potentially causing the pings, knocks and detonations. it may be worth running a tank or two to find out.

i don't know how true this is to our small displacement engines compared to car small/big block v8 engines, but in say a small block chevy, the maximum compression ratio for regular 85, or your region's equivalant lowest octane rating is, is about 9.5:1 which is about 190psi +/- 10psi per cylinder. i know that the stock compression ratio is 8.5:1 or 150psi for both my suzuki gs650g and my kawasaki kz1000m1, allowing for lower octain fuels.

Even properly jetted for a rich mixture, the BB 1100's still run hotter. Big Coolers and SERIES R/R's seem to help the most.

 

[60ratrod]

i was just suggesting it because running to low of an octane can really do some damage on higher compression ratio motors. personally in his shoes, i would try a tank or two of premium to see what that does to the operating temp since the kit bumps not just displacement, but compression.

 

[posplayr]

i was just suggesting it because running to low of an octane can really do some damage on higher compression ratio motors. personally in his shoes, i would try a tank or two of premium to see what that does to the operating temp since the kit bumps not just displacement, but compression.

With my 1166 at CR=10.25:1 premium is a must. I dont know what the CR is for the 1085 kit but I'm guessing he needs to run premium else .....

 

[60ratrod]

it may not drop the temps greatly, but it should drop them a noticeable amount.