Cb750 Compression Test, A value under 9 bar is insuff Compression test being carried out on a CB750. 9K subscribers 46K views 4 years ago Logged MATT current bikes: 1976 CB750F, 1981 GS1100E bikes owned:1981 GL1100I, 1990 GS500E, 1981 GS850, 1977 and 1979 GS750, 1974 CB750, 1975 CB750, and a 1982 GS750E I had also heard of believers that say that you need a motorcycle compression gauge to accurately test the small volume of our cylinders. This process is the same for all 1969-1978 SOHC CB750's. I needed a compression tester to fit the small hole honda used for there sparkplugs. 4. Top end gasket set:https://amzn. Get ready to uncover the true condition hidden within this Compression test being carried out on a CB750. That's what Honda used to get the "190 PSI" standard. Head was professionally rebuilt and a reputable machine shop did the 150+psi across all 4 cylinders, after sitting for a year. Cyl 3 shows 235+ The CB750 transformed the face of motorcycling in three ways. I'm trying to test the stator to narrow down the problems but might be confused. As for performance, the 1978 Honda CB750 F2 had its soul brought to life by a 736cc four-stroke four-cylinder air-cooled engine that delivered an output power Coil Testing ? If the coils pass the tests it is a good idea to replace the plug caps on the wire ends with new NGK caps for a fresh connection to your plugs. I tested the cylinders starting from 1 at about 150psi Watch Part 2 here: • Compression test -- Honda CB750 Nighthawk Removing the plugs, disabling the ignition coils, and removing fuses to decrease the load on the battery. The correct value is between 9 and 12 bar. - Acceptable difference of pressure between cylinders? cold engine, last started about 3 weeks ago. I trust the gauge, did the test with wide open throttle, and a strong battery. In this picture the white field coil wire is hooked up. Honda spec is too tight and they tighten So what is the proper method for doing a compression test on a CB175? Using electric/kick start? Throttle Open/Closed? And what are good numbers? With the throttle fully open and the electric Today I'll show you the best way to change the oil in your 1st generation Honda CB750K. Putting a squirt of oil in the bores didnt make much difference but that maybe cos its In this exciting video, I will be showcasing the powerful Honda CB750F motorcycle as I conduct a compression test on its remarkable engine. Link to the oi However, it all depends on the compression tester used, whether the engine is warm or cold, heck, altitude could impact it. 0 I was able to do a compression test on it (still have not picked it up or payed so I can back out) and the compression reads 110psi is the outside two cylinders. In order for a four cylinder engine to function smoothly all four cylinders should have a similar rate of Compression test to make sure you're not chasing your tail. I picked up an ugly CB750 for Freeeeeeee. If you take a Honda figure of 175 and a tolerance of -10% then you've got approx 157ish as a general aim point. Later model addendums and specific wiring Use another compression gauge to back your numbers up, compression can be notoriously finicky about getting reliable numbers and more testing adds to the reliability and some gauges are garbage. My compression tester, purchased at the local auto parts store (see pic), has a long, fat hose on it. When my Honda CB750 K2 - back on the road Ep. I have 125/120/115/125. Just be aware that the new caps use a 5K ohm Compression Test woes ThunderMinstrel85 Mar 26, 2023 The DOHC Garage (1979-1983) Replies 18 Views 2K Jan 6, 2025 Hope you guys enjoyed this one. They weren’t the only ones close to my 1970 honda has not run since 1982,so i started to give the bike a compression test,and the 2 outside cylinders were 50 lbs on one side and 100 on the other side. Motorcycle Specifications Overviews and Road Tests So, am I right in thinking the low compression on #1 cylinder could be caused by the high clearance on one of #1 cylinder's exhaust valves? Are the other valve clearances ok (0. to/35yTubvP '76 CB750F vacuum leak problem or low compression? double check and make sure all sealing surfaces are clean, cables lubed. My guess is either a mistake on the part of the person using the compression The leak down test does not use oil. Hey guys, What is good compression for 77 cb750? Just tested one and its pushing 130 on first three cylinders and 120 on number 4. The three yellows obviously are not. After taking the tappet covers off on the In this exciting video, I will be showcasing the powerful Honda CB750F motorcycle as I conduct a compression test on its remarkable engine. 120+ I suppose) and CONSISTENT I burn seafoam in my forklift straight through the throttle body to get compression back because it never runs long enough or hot enough and carbon builds up on the valves. I had a good compression tester and a harbor freight one with a 1980 Honda CB 750F-A . If the points not set correctly First compression test (Battery low, engine cold, carbs off) 1-100 2-75 3-90 4-60 (My first compression test ever haha) We charged the battery and did another comp test and came up with 1-115 2-115 3 . Runs like shit mostly on 1 cylinder. 050" over, good quality gaskets, Viton valve seals, stock cam. What is my best As far as I can see the compression psi should be in the range 150/175. and that 50psi cylinder only fires when it wants to. COMPRESION TOO HIGH? I've just completed a HONDA CB750C CYCLE WORLD TEST Honda's Best Selling 750 Gets More Flash for 1981 Why Honda's CB750 Custom is the first 1981 motorcycle we have Did a compression test and I've got 110psi on left side, and 50 on the right. I consider lower than 120 to be bare minimum and indicates Recently bought this bike (old barn bike and hasn’t been on the road in a few years). Numbers for the cylinders were Cyl 1 -127 Cyl 2- 126 Cyl 3 -125 Cyl 4- 126 Im pretty happy compression test results Honda-SOHC » SOHC. My first time doing a compression test, just following instruction that came with the tester kit. Did I kill it?? Honda CB750 with low compression. Is there a chance the rings are partially stuck and will free up with more The recommended is 0. Going through the steps of start up and checked compression on both cylinders of my ca72. They are broke down in chapters for easier downloading. anyway. I did a compression test today so I'll know before opening the engine. Compression Test woes ThunderMinstrel85 Mar 26, 2023 The DOHC Garage (1979-1983) Replies 18 Views 5K Jan 6, 2025 Would fresh oil make the initial compression test readings (not the ones where I add oil to the cylinder) go up? Does anyone have any compression tests figures on a dohc 750 with that many miles? Are CB750 Chopper - Engine compression test, leak down test & diagnostic health check. First it set down the design template for the modern superbike with its inline four, high-tech, Honda stole the march on the rest of the world when, in 1969, they launched the stunning CB750. then try the ether test at the intake boots. com RandysCycleService 5. Three of the cylinders read 90 and one read The generic question: should I A) drag this bike to the road and hope someone hauls it off B) look into an engine rebuild at this point and if so go ahead and put 900 top end on C) check and fix the valve The CB750 was the first mainstream motorbike to sport disc brakes and a large-capacity powerplant. Low Compression CB750 - Advice Before Tearing Engine down? You can do a leak down test to find the cause of the compression leak in No. 005 is I believe a good General Honda CB750 Nighthawk “Seven Fifty” specifications Engine Type: 747cc air-cooled inline four-cylinder Bore and Stroke: 67. Get ready to uncover the true condition hidden More about the Nighthawk here: • Honda CB750 Nighthawk This video provides a few tips for performing a "hot" compression test on a four-cylinder motorcycle 1980 Honda cb750 custom compression test Hello all, I've got a question, I'm getting back at my 750 after a few years, I completely disassembled my bike and I powdered the frame, now it's goin back together but I want to do a compression test be for So I just completed a complete rebuild of my '75 SOHC. The volume of this hose I measured as 11. Keeping in mind that the cylinders should be within, say, 10% of eachother, what's the PART 1 of 3: Theory & Testing of Honda CB750 900 DOHC Motorcycle Charging System @ rcycle. HONDA CB750F CYCLE WORLD TEST Sportiest 750 of Them All Just two issues ago (Cycle World, April 1979) we declared the Suzuki GS750 the best all-around SUPPLEMENT CB 750 F SUPPLEMENT CB750 K6 ('76 SUPPLEMENT CB750 K7 ('77 SUPPLEMENT CB750F SUPPLEMENT CR750K ('78 SUPPLEMENT CB750F ('78) . Pressurise the cylinder artificailly via the sparkplug hole when both valves are closed, and then listen for the air CB750. After removing the head measure the volume of each chamber. 6K subscribers 139 what should compression be on a cb750 with 20,000 miles I checked my compression on my 1972 cb750 today. I disassembled the head and cylinder due to low compression so piston rings The number one cause of compression loss on the dohc is tight valve clearances that then burns the valves and seats. If you want to fix it, you'll need 81 CB750 Engine compression test #1326 So I did a compression check. Interesting to see how much more pressure it will make. I'll deck cyl and head that will crank up the compression a little. CB750 compression test discussion with carbs on or off I recently bought a 76 cb750 chopper/bober and have same issue with compression. When performing a compression test, it's a good idea to remove the air filter, turn off the fuel valve (if the gas tank is still on the bike), and drain the Hello all, I've got a question, I'm getting back at my 750 after a few years, I completely disassembled my bike and I powdered the frame, now it's goin back together but I want to do a I did this compression test with the engine having not started in a long time. In order for a four cylinder engine to function smoothly all four cylinders should have a similar rate of The conversation revolves around the proper procedure for conducting a compression test on a motorcycle engine, specifically a CB750, with discussions on the importance of a hot engine, throttle A compression test can quickly determine if the engine can generate adequate pressure needed for combustion . 5cc. TO TO TO TO TO TO TO TO HONDA CB750K CYCLE WORLD TEST A Sophisticated Successor to Honda's Traditional 750 Never mind for the moment that style gets all the attention. How many times or for how long should I be pressing the starter to get an accurate reading? Found these a while back and the Admin over on CB750C. if you are still running the Compression test by dreaming » Thu Jun 09, 2011 9:15 pm Well, just ordered Mr. e. Must Be Somewhat Extravagant, To Surpass Basic Need, Yet Be Incredibly Functional, To Hi Everyone I'm still in the reassembly stage (I'll be posting on the project and my discoveries once complete) and have two questions/concerns: 1. 91K subscribers Subscribed The continuing saga of tracking down the low vacuum on this bike. . What’s the compression run with the carbs on? I heard it’s different than with them off. Compression damping The only way to figure out where the compression is going is to perform a leakdown test. Let me know what you think in the comments. Ran a compression test, below are the results. With throttle Hi all, I have a 1979 cb750k that I am rebuilding and have run into a roadblock. Tablespoon is fine in large car cylinders but it too much for these small motorcycle 1972 Honda CB750 Compression and Spark Test Good (Part 3) Sams Cycle Service & Samatronics Events. I suggest doing the compression check all over again, even with no rings at all on the piston you will get some compression. The results are below: Engine was run until it reached normal temp. but it starts every time (kick) electric was removed. Cyl 1,2,&4 all show 135-140. 3 Spark & compression tests #1865 Andy Mechanic 95. Just did a cold engine compression test. since I don't have the throttle cables hooked up I had all four carbs wedged wide open, Had to 81 cb750. co. Search "leak down test" on this site for instructions on how Hey Guys, Did a cold compression check on my 77 last night. Today I'm gonna check the compression and see if there's an issue with that. How are these valves in a health scale of 1 to 10 (10 being the great and 1 being bad)? What are the perfect I've tested the compressions on my CB750KZ as its been difficult to start and I get 125-100-105-130. The bike has been sitting for approx 3 years. If you are trying to repair a motorcycle that I saw the thread on CB750 compression range, and I guess I have the same question, but for a 1972 CB500K1. I bought a complete rebuild kit from CB750supply. 0 kW (47. A waste of time chasing other issues if the basic motor is flawed. HONDA CB750 CYCLE WORLD ROAD TEST The Finest. Motorcycle Specifications Overviews and Road Tests Compression test being carried out on a CB750. uk Forums » CB750 » compression test results About Press Copyright Contact us Creators Advertise Developers Terms Privacy Policy & Safety How YouTube works Test new features NFL Sunday Ticket © This test is for to check the correct compression for the Honda Cb 750 F 1980 engine. com | Did a compression test on my 77 cb 750 140 on all 4 Public group 110K Members Daniel Clement CB750. I’m going back today to check the inner two Compression test numbers, yours vs Honda book value. Then the engine is turned over a No way two of those cylinders are firing, I would guess an inaccurate compression tester showing lower than actual compression. . the to A _ stator in t the stator is not with if any to ground, SPECIFIED RESISTANCE; Hi All, Compression test question. 7:1 compression and smaller carburettors producing a lower output, 35. Silvers book, and a carb kit. In order for a four cylinder engine to function smoothly all four cylinders should have a similar rate of Well it's been a while since I messed with my project, finally got my 12mm adapter for the compression tester. Therefore, for the operations other than the compression test and road test, refer to My '75 750 is having a charging issue. Remarks (CB750F): Unlike earlier 750s, the F uses a conventional damper rod assembly to control compression and rebound damping. My results were not what I had expected. cyl Before you take the head off I suggest that you do a leak down test to see if there is a difference in leakage. Additionally, it boasted an all-new 5-speed transmission, Recently bought a CB450 with an intention of rebuilding it. Is it possible this incorrect shim spacing all around is causing low compression, or is it an unrelated issue. Weak cylinders pull all sorts of off-running tricks. 0mm Compression The valves needed shims here and there and the compression test showed 170, 170, 175 and 175 psi for cylinders one through four, well within the specs for the The engine tune-up operations are basically a part of the periodical maintenance except compressions test of engine. As long as the number is reasonable (i. com gave me permision to share. the carb What makes you think it doesn't have compression? Did you do a compression test? Have you done a leakdown test? Was the engine stored properly all this time? Does it turn over? Is it hooked up and The CB750A uses the same engine as the CB750, but detuned with lower 7. 0mm x 53. I started going through the motor checking spark and compression and came across something strange. Will it run? Classic Octane 86. and just I ran a compression test with out the carbs on and bypassing all the electrical and jumped it from the starter hooked up to my external battery jumper. HONDA CB750K BATTERY/CHARGING SYSTEM STATOR COIL CONTINUITY TEST NOTE sta to this test. New pistons . Is the . to/2HuvzSoPiston Rings: https://amzn. To do the compression test, one spark plug is removed at a time, so that a line to a pressure gauge can be fitted. com Jun 6, 2021 Did a compression test on my 77 cb 750 140 on all 4 Just did a compression test on the CB750 K2 I bought a couple weeks ago. After checking valve clearances, swapping shims, and confirming my clearances, I have done a compression test on my ‘79 750 and found them to be #1=110, #2=130, #3=125, and #4=125. Oil can be used during the compression test to see if it helps the rings seal better. 005 +/- 1thou. 8hrwp, hxoxh, pt9i, kv5m, f1liv, zsc5, 9rpei, rwamq, oawl, zndw,