GSX1400 Owners .org

Technically Speaking => General Technical discussion => Topic started by: Snapey on Saturday, 27 June 2020, 10:33 PM

Title: The bastard won't start
Post by: Snapey on Saturday, 27 June 2020, 10:33 PM
Not the 14 but the bloody Clubman 7.

What I have is a big port Toyota 4A-GE twin cam 1600cc engine with a set of 1999/2000 Honda CBR600 carburetors I just fitted. I'm not using the fuel pump as I think there's too much pressure so I've set up a gravity feed for the fuel, timing is spot on, as are the points and new plugs but this engine won't run with any throttle. It wants to start but as soon as any throttle or choke is activated then the firing stops.

I was assured the engine was a strong runner but after a compression check I find that extremely doubtful as all cylinders are around 60 PSI. I just want to hear it run before I rebuild it so I'm wondering if the low compression is my starting problem.
Title: Re: The bastard won't start
Post by: Hooli on Saturday, 27 June 2020, 11:05 PM
60 psi does sound very low, are you doing the check right?

I'm not sure myself but I think you need full throttle when you do it, or you do get low readings.

Title: Re: The bastard won't start
Post by: Snapey on Sunday, 28 June 2020, 12:40 AM
Quote from: Hooli on Saturday, 27 June  2020, 11:05 PM
60 psi does sound very low, are you doing the check right?

I'm not sure myself but I think you need full throttle when you do it, or you do get low readings.

Sure was full throttle .... the carbies & manifold weren't on the engine. :) Even at 60 psi I think it should start.
Title: Re: The bastard won't start
Post by: Hooli on Sunday, 28 June 2020, 03:04 AM
Ahh gotcha.
Title: Re: The bastard won't start
Post by: Irish in Oz on Sunday, 28 June 2020, 05:12 AM
Stick some rags in the exhaust ports and see if there is any difference.
Title: Re: The bastard won't start
Post by: grog on Sunday, 28 June 2020, 06:50 PM
Snapey, 60 psi is very low. Ive always been told 100 is minimum to run. Does it have valve clearance? If clearance ok, what about a squirt of oil in each cylinder, stuck rings. Pretty much the only two reasons for low comp as you would know. They are great revvy motors.   
Title: Re: The bastard won't start
Post by: grog on Sunday, 28 June 2020, 07:01 PM
Double post, sorry. Mid 80s drove a 4AG, injected. The ECU was faulty, no rev cut out. Took the taco needle to 6 o clock which we worked out around 12 th. revs. Mighty motor. My little corolla with 4AFE is just as good, can rev lots.
Title: Re: The bastard won't start
Post by: Snapey on Sunday, 28 June 2020, 07:08 PM
Even with the compression so low I think it should start. I think my problem is vacuum related but fixing that has me confused. I've got lots of hoses that need to be blocked off or attached to something buy no idea what or where.
Title: Re: The bastard won't start
Post by: KiwiCol on Sunday, 28 June 2020, 07:43 PM
Squirt some 'start ya bastard' in the inlet & see if she likes that.
Title: Re: The bastard won't start
Post by: Snapey on Sunday, 28 June 2020, 07:57 PM
Quote from: KiwiCol on Sunday, 28 June  2020, 07:43 PM
Squirt some 'start ya bastard' in the inlet & see if she likes that.

I thought about it Col but if it's lack of vacuum that's the problem then I can't see it working. Worth a try though.
Title: Re: The bastard won't start
Post by: Snapey on Monday, 29 June 2020, 11:16 AM
Start ya bastard ... useless.
Title: Re: The bastard won't start
Post by: KiwiCol on Monday, 29 June 2020, 04:52 PM
Oh well, least you would of got a bit of a buzz off the fumes!  :imrgreen:   :cheers:
Title: Re: The bastard won't start
Post by: Batkwaka on Monday, 29 June 2020, 05:02 PM
Probably way off target but I had a similar issue with a ZZR1100 once.
After I had stripped all the bodywork, given the bike a full clean and put it back together, it would idle but anything over 2500rpm and the engine would die.
I had forgotten to reconnect the Ram-Air tubes from the front and that was the cause of the problem, not sure why or if it's applicable in this case but might be worth looking into the air galleries.
Title: Re: The bastard won't start
Post by: Snapey on Monday, 29 June 2020, 06:32 PM
Quote from: KiwiCol on Monday, 29 June  2020, 04:52 PM
Oh well, least you would of got a bit of a buzz off the fumes!  :imrgreen:   :cheers:

Bloody ether Col reminds me of operating theatres when I was a kid
Title: Re: The bastard won't start
Post by: Irish in Oz on Monday, 29 June 2020, 08:20 PM
Quote from: Snapey on Monday, 29 June  2020, 06:32 PM
Quote from: KiwiCol on Monday, 29 June  2020, 04:52 PM
Oh well, least you would of got a bit of a buzz off the fumes!  :imrgreen:   :cheers:

Bloody ether Col reminds me of operating theatres when I was a kid

They stop using ether in 1920.