MSteenJ Posted June 21, 2018 Posted June 21, 2018 Unfortunately as of today as i was going to clean out the head and lap the valves, i discovered a crack between the sparkplugwell and an inlet valve in cylinder 2 and 3. So i guess ill be needing a new head. The rest of the engine looks REALLY good, pistons, walls, cams, rockers etc. What head will be my best option? I've read that a GSXR1100 (86-90) or GSXR750(87-89 short stroke) would be a good improvement cause of better airflow. Are one of these a straight bolt on or what should i be expecting? Quote
Duckndive Posted June 21, 2018 Posted June 21, 2018 1 minute ago, MSteenJ said: Unfortunately as of today as i was going to clean out the head and lap the valves, i discovered a crack between the sparkplugwell and an inlet valve in cylinder 2 and 3. So i guess ill be needing a new head. The rest of the engine looks REALLY good, pistons, walls, cams, rockers etc. What head will be my best option? I've read that a GSXR1100 (86-90) or GSXR750(87-89 short stroke) would be a good improvement cause of better airflow. Are one of these a straight bolt on or what should i be expecting? Those cracks are quite common ..most don't worry about them and carry on using the head.... 2 Quote
johnr Posted June 21, 2018 Posted June 21, 2018 and the gsxr engine is totally different to thee gsx one so the heads arent a swap, although it has been done but with a lot of work. 1 Quote
MSteenJ Posted June 21, 2018 Author Posted June 21, 2018 I was hoping for a fairly easy swap, dang it. The reason i think i need a new head is because these two cracked cylinders have 40psi while my other two good ones has 130. Valves are newly adjusted and pouring a bit of oil into the two bad cylinders didn't really help (maybe 50-55psi). Should i just "hunt" for a new original head? Quote
johnr Posted June 21, 2018 Posted June 21, 2018 that crack wont cause the loss in compression that you have. id be looking for some more pistons first. 1 Quote
Swiss Toni Posted June 21, 2018 Posted June 21, 2018 (edited) That was common with the Triumph 8 stud alloy heads. No effect on performance, so lived with it. 9 stud heads solved the problem. Could be welded, but not cheap. As John says, might be worth looking farther afield to find the cause. Edited June 21, 2018 by Swiss Toni 'Fat fingers' 1 Quote
Gixer1460 Posted June 22, 2018 Posted June 22, 2018 Personally i'd say those valves and seats have been cut / lapped to death! The valves look pretty recessed and engines these days don't get 'coked up' with carbon like they used to - unless its burning oil ........ which with the low compression is a possibility. I think there is further investigation required - should have done a leak down test before you pulled the head - that would have pointed to valves or rings ........ wouldn't have stopped a strip down but you'd be fixing a known problem. BTW - that crack ain't it! 2 Quote
MSteenJ Posted June 22, 2018 Author Posted June 22, 2018 Thank you all for your replies, still learning about basic engine knowledge. Could it maybe be that the cracks have affected the sparkplug holes threads? The reason i might think this is because i've tried torquing(10nm) the spark plugs in and the two good cylinders are all good but the two bad ones sit 2-3 threads height further up. Can this be where the chamber is loosing so much compression? Btw. If i keep this head i will be getting new valves then, thank you say what now!? 1460 Quote
Gixer1460 Posted June 22, 2018 Posted June 22, 2018 You may want to sit down when you price up the valves and you'll still maybe have the same problem - the valve seats are worn out ie. the hole is too big due to the valve seat angle being cut too deep. I've never had a problem winding a plug into a head - cracked or not........ 2 or 3 threads up and the plug won't be seating so running it like that, you'd have to be deaf not to hear the compression escaping. Possibly its a crossed thread ..... or 2 - that'll stop a plug seating! Quote
Duckndive Posted June 22, 2018 Posted June 22, 2018 (edited) 23 hours ago, johnr said: and the gsxr engine is totally different to thee gsx one so the heads arent a swap, although it has been done but with a lot of work. No it’s relatively easy to do.. .but I would not recommend for it for a road bike Air Cooled Bottom End and block Fitted with GSXR 1100 Pistons Topped of with GSXR 750 Dot Head......Simples ........... Edited June 22, 2018 by Duckndive 1 Quote
gsxkat Posted June 27, 2018 Posted June 27, 2018 Surely the cheapest option would be to buy a used cylinder head if the valves seats are too worn? Quote
gsx1100e Posted July 25, 2018 Posted July 25, 2018 On 6/22/2018 at 8:41 PM, Duckndive said: No it’s relatively easy to do.. .but I would not recommend for it for a road bike Air Cooled Bottom End and block Fitted with GSXR 1100 Pistons Topped of with GSXR 750 Dot Head......Simples ........... Has anyone tested gsx-r head on Road use? It is desinged to be oilcooled, still could it work in oilcooled motor in road use. Quote
Duckndive Posted July 25, 2018 Posted July 25, 2018 1 hour ago, gsx1100e said: Has anyone tested gsx-r head on Road use? It is desinged to be oilcooled, still could it work in oilcooled motor in road use. I did run mine on the road a few times but the head got very hot... ...which I would guess was down to lack of oil flow..... in the oil boiler there is a lot of oil volume that is directly pumped to the head. .the air cooled motor even with uprated gears get's no ware near close to the same volume Quote
Gammaboy Posted July 26, 2018 Posted July 26, 2018 10 hours ago, Duckndive said: I did run mine on the road a few times but the head got very hot... ...which I would guess was down to lack of oil flow..... in the oil boiler there is a lot of oil volume that is directly pumped to the head. .the air cooled motor even with uprated gears get's no ware near close to the same volume The oil cooled motors basically have 2 pumps side by side - once for low pressure cooling flow to the head, the other for high pressure feed to the whizzy bits. Quote
gsx1100e Posted July 26, 2018 Posted July 26, 2018 8 hours ago, Gammaboy said: The oil cooled motors basically have 2 pumps side by side - once for low pressure cooling flow to the head, the other for high pressure feed to the whizzy bits. So that modification is only for drag racers. Quote
R1guy Posted December 30, 2023 Posted December 30, 2023 On 7/25/2018 at 4:41 PM, Duckndive said: I did run mine on the road a few times but the head got very hot... ...which I would guess was down to lack of oil flow..... in the oil boiler there is a lot of oil volume that is directly pumped to the head. .the air cooled motor even with uprated gears get's no ware near close to the same volume @slayer61- have you considered this? Quote
slayer61 Posted January 2 Posted January 2 On 12/30/2023 at 1:51 PM, R1guy said: @slayer61- have you considered this? I think R1guy is asking about my thread to document doing just this... adding a DOT head to my GSX My bike isn't a commuter, or an all day rider. I'm too old and fat for all that. I do enjoy a quick trip up & down the road, however. I have added the 750 pump, and cooler to the mix. I'll keep compression and timing in check in an effort to keep heat at bay... or at least to a minimum on a short trip. Thanks for worrying about me R1guy! Quote
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.