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Blowing exhaust gaskets


jonboylaw

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1800 RK crossflow. Looks like the exhaust gasket is blowing on cylinders 2 & 3.

 

Questions:

 

1: will this cause the excessive amount of bangs and pops I get on over run?

2: I get the occasional spit back through the carbs, is this a side affect or is it a symptom of the timing being out?

3: Replacing the gasket, is it just a case of buying the correct replacment, lossening off the Hex Bolts, removing bolts from 2 & 3 and fitting the gasket and bolting back up?

 

Anyone offer advice?

 

 

Thanks in advance.

Jonathan

 

-----------------------------------

1db too loud ! ☹️

Bastxxd Santa never delivered the Raceco!!!! ☹️

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To answer your questions...

 

1, Yes! The leaky gasket allows air to enter the exhaust and akes for "pops and bangs" (great arn't they 😬)

 

2, Spitting carbs is usually a symptom of a lean mixture. However most tuned Xflows spit a little. Mine seems to be affected by the weather!

 

3, Yes, easy as that. The 7 workshop sell "copper" gaskets as recommended by Roger King. These last a LOT longer and can be reused in necessary. Cost is around £25 a set.

 

Hope that helps

 

Steve

SE7EN-UP!

(It'S NOT Green!)

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Cheers Steve,

 

Not sure I am running lean but will get the car over to RGS for a rolling road session in the spring.

 

Thanks for the info on the gasket sets. I'll invest in a set, whilst the manifold is off I might as well "match" the gaskets to the manifold.

 

I'll let you know how I get on.

 

Cheers,

Jonathan

 

-----------------------------------

1db too loud ! ☹️

Bastxxd Santa never delivered the Raceco!!!! ☹️

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Mainly at low revs, but also mid too. I have recently noticed that it has "stalled" when flooring the throttle, basically engine dies for a fraction of a second when excellerating hard. Possibly the leaking gasket, but I think a tune up is needed soon.

 

Next question is before or after the new silencer

*biggrin*

 

 

Jon

 

-----------------------------------

1db too loud ! ☹️

Bastxxd Santa never delivered the Raceco!!!! ☹️

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Steve,

Just did a seach for xflow gaskets and have seen a copper set of cnc produced gaskets for £14, got be ad cheaper alternative to the 7 workshop ones at £25.

 

link is below:

 

http://ferriday.co.uk/cnc/production.html

 

I might see if they would offer a bulk buy if other x-flow owners are up for it.

 

 

Gavin,

I was expecting this, just need to raise the finance for the Raceco Santa never delivered.

 

 

 

Jonathan

 

 

-----------------------------------

1db too loud ! ☹️

Bastxxd Santa never delivered the Raceco!!!! ☹️

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Jonathan,

Good find!!!

 

I'd be up for a set if a bulk buy goes ahead.

Not a bad price, they are already around £10 cheaper than the ones advertised in Low Flying.

 

Does anyone know if the ones advertised in LF are any different from the ones mentioned above?

I guess they must be due to the price difference *wink*

 

Steve

SE7EN-UP!

(It'S NOT Green!)

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I always thought that spit backs thru the carb were often due to running too rich...???? the mixture when too rich burns slowly and sometimes is still buring when the inlet valve opened, causing a spit back... maybe its just an old wifes tale but i'm sure i heard it some where *confused*

 

'Pinky Pics' here

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I have contacted Ferriday to see if they are interested in a group buy discount 😬. I'll post the reply here once I know.

 

Jonathan.

 

-----------------------------------

1db too loud ! ☹️

Bastxxd Santa never delivered the Raceco!!!! ☹️

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Jonathon,

When the manifold is partially off, suggest remove the system completely. The flanges will not be straight. This is the most common cause of exhaust gaskets blowing. Take to a machine shop who will true this up for £15 or less if they like you. Since trued,I have never had to replace this gasket.

Should add that locking the cap head manifold bolts is essential. Used to wire lock ( drill before use),but have found common thread lock seems to survive the heat adequately.

 

The RK copper gasket seems to be the same as others , just bigger.

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Norman just directed me to this posting *thumbup*

 

Like all the similar posts I became increasingly pi**ed off with replacing c.6 gaskets for cylinders 2 & 3 - never a problem with 1 & 4. I also used the copper type from Roger King and whilst they lasted longer they did not cure the problem.

 

As Norm points out I kept moaning about the problem to a mate at the regular Friday night drinking and session. Fortunately this friend is an engineer with a well equiped workshop and after about 3 hours trial and error one Saturday afternoon he made a bracket that supports the angled section of the primary pipes.

 

We decided this was easier (at the time) than trying to fit a support between the frame and the pipe just in front of the silencer.

 

If anyone's interested I'll take some pictures and put them in a web album for all to see. *idea*

Rog

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Roger,

I would be very interested in seeing some pictures.

 

Can you post them or send a link via e-mail. is it weld on? and what are the chances of remanufacturing one?

 

Cheers,

Jonathan

 

-----------------------------------

1db too loud ! ☹️

Bastxxd Santa never delivered the Raceco!!!! ☹️

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Ok, so anyone interested in a bulk buy?

 

"The price of £14.00 per set will come down to £12.50 if 10 are ordered, or £9.50 for 20 sets.

 

These gaskets are 0.9mm thick, with a 33mm aperture (to cope with port modifications) and should last the life of the engine regardless of how many times they are removed & refitted. If a different aperture diameter is needed it's no problem, just a couple of days for delivery."

 

If there is interest then I will post in Chit Chat.

 

Jonathan.

 

 

-----------------------------------

1db too loud ! ☹️

Bastxxd Santa never delivered the Raceco!!!! ☹️

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I guess even a 0.9mm solid bit of copper should be more effective than the "standard" item.

My gaskets always seem to blow from between the two outer skins - they just open up. Nearly always happens on 2 and 3 and doesnt seem to matter if the gasket is a one or two hole version.

 

 

Does anyone here use "solid" copper gaskets?

 

Steve

SE7EN-UP!

(It'S NOT Green!)

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I'll try and get the pictures sorted out asap.

 

I'm not sure any gasket will solve the problem - to me it seems to be a fundamental design flaw with the central manifold bolts being across the horizontal and the (unsupported) weight of the primaries and can 'pulling down' on the joint, a gap is bound to appear between the head and primary exhaust flange - hence the need for support from below.

 

It should be possible to copy mine - the support is made from steel and two U clamps welded together and attached to the lower rear engine mount. Pictures will make it clearer.

 

Rog

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