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

[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.

[Big T]

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 .....

Jim
My 78 has a 1085 and burns regular. That may be because my machinist spent an evening cc ing the head and chamfering the edges of the combustion chamber, which eliminates a hot spot and slightly lowers the CR

[posplayr]

Jim
My 78 has a 1085 and burns regular. That may be because my machinist spent an evening cc ing the head and chamfering the edges of the combustion chamber, which eliminates a hot spot and slightly lowers the CR

Wiseco say the K1085 is a 10.25:1 same as the 16V 1166 so I don't know other than mine will run on regular but will also ping. Talk to Bill about headwork on his 1166 that he blew up on the way back from Lost Coast on the rally to Mt Shasta. He was running regular and he barely made it back to Highway 101 before it finally gave up.
Could have been the gas, or could have been an overzealous machinist skimmed his head too much.

[Nessism]

For people that think a R/R can affect oil temperature check this thread...http://www.thegsresources.com/_forum...ffect-oil-temp

I performed back to back testing (30 mile ride on a hot day) using both a series and shunting R/R and measured oil temperature along the way.

Result: the R/R had NO IMPACT on oil temp. Period.

[posplayr]

I added Fjbj40 to the list of people reporting reduction in operating oil temperature after installation of a SERIES R/R. This is somewhat of a first ! Most other people I know, having done so, have had such results with the Compufire SERIES R/R and generally on a 16V 1100E. In principle any SERIES R/R and bike close to thermal overload (Big Blocks especially) should see the benefit.

If your bike already runs cool (under 240 degF) then the series R/R will probably do little. If the bike runs at a steady rate (not talking about a short term dash) at an elevated temperature (270+ degF like the OP describes) the small differential of the SERIES R/R is enough to drop your operating temp. It is a pretty fine balance.

The bike
1979 GS1000S, with Standard pipes (yes proper originals), and standard airbox and filter with lid on, Dynateck Electronic ignition (I've put a strobe light on the timing and it appears fine going fully advance at around 3500rpm).

The change
I've recently added a Wiseco 1085 piston kit. The bike runs like a train - lots of power, no flat spots, no hesitations up to redline, idles well.

The problem
If I ride for about 20-30 minutes at 60-80km/h 35-50mph on a COOL day with no stop-start traffic the oil temp gradually keeps rising (this model is the one with the oil temp guage) until it reaches almost 170C (around 330 deg F) before I stop and let it cool down. If I take it onto the freeway or non-urban roads and ride at around 100Km/h (60mph) or above the temp drops to around 100 deg C (212 deg F) or less.

Fjbj40 confirms temp reductions using the SH-775 and on a 8V no less.

http://www.thegsresources.com/_forum/showthread.php?161397-Compu-Fire-SERIES-R-R-Install

HIGHLY RECOMMENDED FOR A Warm Running 16V GS1100/1150. For you naysayers out there. There is a significant temperature drop if you are running stock in the 250-270 degF range (My 1166 went down to 210-220 degF max).

Aprilla but shows back to back temperature drops

UPDATE; Wheat dog has confirmed a nominal 30 degF drop in operating temp for an 83 GS1100ED with 1166 kit after making this change over to the Compufire-Fire R/R
Installed Compufire RR - Way Cool!!

Chef1366 temperature drop results GS1100 with 1229.

http://www.thegsresources.com/_forum/showpost.php?p=2009372&postcount=50

Katman did an install

Compufire "series"
regulator / rectifier
Reduces engine oil temp.

http://www.parts.suzuki-katana.com/

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.

http://www.thegsresources.com/_forum...18#post2192818

For the OP, you might just give it a try. 20degF drops are not unusual and they only get larger drops the worse the problem.

[IanR]

A quick update: I took my bike to a motorcyle workshop where they seem to know what they are doing with older bikes like ours - they build and race bikes of similar ages.

They put it on the dyno, stuck a small diameter copper tube well down the RH exhaust pipe and analysed the exhaust gases.

They showed me that the bike is running well, with a slightly rich mixture right across the range of throttle openings. They suggested that I should leave the jets were they are and install an oil cooler.

So that's what I'm going to do. I'll let you know how I go.