Top resto man and journo Will Bar­ber was asked to re­store a su­per-rare Kawasaki. He shared part one of his story with us.


Will Bar­ber does the busi­ness on this love­able rar­ity!

What we have here is Chris Kitchen’s 1979 Kawasaki Z1-R TC, im­ported into the UK from Aus­tralia in March 2017, and it was my job to get her sorted. So here we go!

First of all, what is the Z1-R TC? Well, she’s less well-known than the 1980s raft of turbo bikes. By 1977-78 the Z1-R was look­ing a lit­tle long in the tooth com­pared to the op­po­si­tion and the rea­son­ing (well, in Canada and the USA) was that to boost (ahem) the bike’s flag­ging sales they should add lots of ex­tra power by slap­ping a turbo on it. Alan Masek was the man behind the plan. A for­mer Kawasaki USA gen­eral man­ager, he’d formed the Turbo Cy­cle Cor­po­ra­tion in Cal­i­for­nia to of­fer bolt-on turbo kits to cus­tomers. He se­cured a num­ber of Z1-RS from Kawasaki and did a deal where he’d bolt-on the kits and sell the bike with­out a war­ranty. So, it wasn’t strictly an of­fi­cial bike – more a dealer spe­cial – and the re­sul­tant ma­chine was over-pow­ered and un­der-en­gi­neered: no spe­cial sus­pen­sion or in­ter­nal mods were made. The turbo it­self (a Ra­jay 370 F40 unit, nor­mally seen on light air­craft) run­ning at 10lb of boost would give the Z1-R an ex­tra 40bhp to deal with – but all power claims vary as to what the TC was ac­tu­ally pump­ing out. Pe­riod road tests of the time re­ported that the bike would be­have like a run-of-the-mill Z1-R un­til 4500-5000rpm be­fore around 6-10lb of boost kicked in and the thing took off… The price was $5000 com­pared to the Z1-R at $3695. Changes in un­der­wear also proved pricey. The re­sult was a way­ward beast that could melt pis­tons and tackle the quar­ter mile in the high 10 sec­ond bracket at over 120mph ter­mi­nal ve­loc­ity… Crazy bike, crazy times. The orig­i­nal bikes were sold in Star­dust Sil­ver and were a mod­er­ate sales suc­cess along with up­dated TC1 mod­els. More was to come with the de­fin­i­tive TC2 – com­plete with black paint job and mul­ti­coloured ‘Mol­ley De­sign’ neon stripes and some im­prove­ments. By 1980, laws had changed in Cal­i­for­nia so no ex­haust mod­i­fi­ca­tions could be made to pro­duc­tion ma­chines. It wasn’t un­til the early 1980s that of­fi­cial ‘Turbo’ bikes from the man­u­fac­tur­ers, such as Honda’s CX500 Turbo would hit the mar­ket. It was a short, sweet and ex­hil­a­rat­ing ride. Christo­pher Kitchen bought this TCII and – via the splen­did Kawasaki Z1 Own­ers Club (Z1OC) UK – got hold of me to help with the restora­tion. So what of me? Well, I am a fully qual­i­fied au­to­mo­tive en­gi­neer and work as se­nior tech­ni­cal author for Bent­ley Mo­tors Lim­ited at the main fac­tory in Crewe, Cheshire. I have been work­ing on clas­sic bikes since start­ing out at the ten­der age of 14, learn­ing a great deal from my late fa­ther who was also an en­gi­neer. I also spe­cialise in in­line four-cylin­der mod­els and forced in­duc­tion is also where my heart lies, hav­ing recom­mis­sioned a num­ber of TCS over the years and thanks to my own past bikes, in­clud­ing an S+S Per­for­mance Sil­ver Saxon, which uses the same turbo sys­tem as the TC. Christo­pher’s bike (if stan­dard, as sug­gested) should only be re­li­able to a max­i­mum of 5psi state of boost, giv­ing around 120bhp, and even then it should have a num­ber of mods, in­clud­ing a 40lb

waste-gate con­ver­sion, an anti-surge gate in the stan­dard sump and other changes. If he wanted more power, then you’d want big­ger changes, in­clud­ing a welded crank, forged pis­tons, a deeper sump, etc. On in­spec­tion the crank was stan­dard but with forged pis­tons (dis­place­ment un­known) with stan­dard studs, head nuts etc. It also had a build-up of sludge in the sump and some dam­age to the cylin­der fins. With the turbo there was some play in the ro­tor, the ‘Spy­der’ ex­haust was cor­roded and had a dent in it and the boost gauge was bro­ken and loose in its bracket. The Mikuni HSR42 carbs needed a good clean and sort­ing too. Un­der the skin many of the elec­tri­cal con­nec­tions were cor­roded, an in­di­ca­tor lens was dam­aged, the front brakes needed an over­haul, body­work was tired and bar grips needed chang­ing to stan­dard again. Set­ting to work, I did a ‘cold’ com­pres­sion test and num­ber three cylin­der seemed a bit low, at just 75psi, but later found that the valve clear­ances on that pot were out. I also knew that I would be shim­ming the valves to fac­tory spec and do­ing a ‘hot’ com­pres­sion test later. The camshafts them­selves were stan­dard (as was the cam-chain ten­sioner) and the camshaft cap re­strain­ing screws weren’t over-tight­ened! Dur­ing strip-down I could see an area of re­pair I’d need to look at on the cam-cover, but once sorted I knew a fresh coat of tough satin black paint would get it look­ing like new. At the bot­tom end of the en­gine the oil fil­ter was binned and – de­spite be­ing told the mo­tor had been drained be­fore ship­ping – three litres of oil was dumped on my clean bike lift! The sludge and car­bon de­posits in the sump looked aw­ful. Af­ter a thor­ough clean and re­moval of all the old paint, work could be­gin on the anti-surge flap for im­proved oil con­trol. Ba­si­cally this in­volves drilling the sump in a pre­de­ter­mined po­si­tion, tap­ping it to 4mm then in­sert­ing a screw from be­neath and seal­ing with in­dus­trial strength two-pack epoxy ad­he­sive to en­sure there’ll be no leaks! From the in­side of the sump, a thin 4mm shim is then ad­hered in place over the screw fol­lowed by a hand-formed alu­minium flap that swivels to de­ter­mine the flow of oil. This is then held in po­si­tion with a 4mm lock­nut. With the anti-surge oil flap fit­ted and in the open po­si­tion, un­der brak­ing and nor­mal rid­ing con­di­tions, this will al­low the oil to flow freely to­wards the oil pump pick-up. Un­der boosted ac­cel­er­a­tion how­ever, the weight of the oil forces the flap shut, en­sur­ing that the oil pump pick-up has a con­stant sup­ply of oil by not al­low­ing the oil to slosh to­wards the back of the sump. If this mod­i­fi­ca­tion isn’t done then chances are the oil pres­sure light will come on as the oil pump sucks air in­stead of oil! The oil pump is also re­moved at this point and checked to en­sure it is within the ser­vice limit and as a pre­cau­tion the seals are also re­placed with new gen­uine Kawasaki items. I also checked the oil pump, which felt fine with no nasty bits in

the strainer. New O-rings were fit­ted and it was then reat­tached. The crank­case breather on the TC also isn’t up to the job, so I wanted to do what I’ve done be­fore, which is to re­move the orig­i­nal breather pipe stub in the cen­tre, and then fit­ting two new out­let stubs ei­ther side of the orig­i­nal. One of the new larger bore breather hoses will go to at­mos­phere, and the other hose will go through a V8 Range Rover flame trap and then to at­mos­phere. The crank­case breather will then be se­cured to the top crank­case via a long sealed bolt com­plete with O-ring. When it came to the turbo, hav­ing had ex­pe­ri­ence of these bikes I knew what could go wrong. Af­ter some is­sues the turbo came apart and the seal­ing be­tween carb and turbo was a mess. Then I found some­one had made an adap­tor plate (with hacked man­i­fold rub­ber) which was well-made but then badly fit­ted to the turbo. The holes (bar two) would be sealed with in­dus­trial strength epoxy. With all this sorted, I fit­ted a nice new in­let man­i­fold rub­ber from Al­lens Per­for­mance. I also de­cided to re­wire the right-hand switchgear to give the turbo bear­ing an eas­ier time on ini­tial fire-up. So, with the kill-switch in the OFF po­si­tion, the en­gine can now be cranked un­til the oil pres­sure light goes out be­fore flick­ing over into the RUN po­si­tion. This en­sures that the oil reaches the turbo bear­ing as fast as pos­si­ble. Fin­gers crossed the ceramic seal is okay, as they are not avail­able at all. With the waste-gate, I was wor­ried that the screw was wound in a fair way, giv­ing a lot of boost. On strip­ping it, all looked well so they were cleaned and painted once more in Si­mo­niz Tough Black satin paint. A 40lb spring was fit­ted in­stead of the stan­dard 80lb spring. With pol­ished parts and the screw now set to a blow-off of 8psi, it was sorted. The ex­haust head­ers were (on my sug­ges­tion) nickel, not chrome plated, mean­ing Solvol will be able to at­tack any ‘blue­ing’ of the ex­hausts. A copy of the orig­i­nal boost gauge was sourced to re­place the dam­aged orig­i­nal along with re­place­ment hoses. The fuel sys­tem is sorted by fit­ting a larger-bore fuel valve (4.8mm up from 2.3mm) and ul­tra­son­i­cally clean­ing the Mikuni carb. Handy this is fit­ted as it costs around £300 and is bet­ter than the Bendix orig­i­nal. The fol­low­ing com­po­nents have now been changed: main jet – from 220 to 240. Jet nee­dle – from 85 to 97. Pri­mary jet – from 30 to 25. The float height has also been set at 19mm and the car­bu­ret­tor now re­built ready for fit­ment. I also fit­ted a new choke ca­ble. I use one from a Honda NSR125R – like the one I fit­ted to my Sil­ver Saxon and mounted on the left-hand side of the en­gine. I also used my Ven­hill ca­ble kit to add a pull ca­ble to the throt­tle set-up. The con­trol of open­ing and clos­ing the slide MUST in­clude a pull ca­ble. If this is not ad­hered to, there is a chance that un­der boost con­di­tions the slide will stay open, caus­ing full throt­tle op­er­a­tion even when the throt­tle is closed! I now turned my at­ten­tion to the air-fil­ter set-up. The orig­i­nal and ex­tremely rare tri­an­gu­lated air fil­ter was only ever fit­ted to the TCII (Mol­ley) model. Un­for­tu­nately, this had been re­placed with a K&N air fil­ter from a car! The air fil­ter fit­ted to the TC1 (Star­dust Sil­ver) model was of the con­ven­tional round type and only the TCII had this gor­geously shaped fil­ter fit­ted. I was not go­ing to be able to repli­cate the tri­an­gu­lated ver­sion due to the com­plex curves so I sug­gested mak­ing an ex­act replica of the round TC1 air fil­ter like I did for the S+S Sil­ver Saxon. While not only repli­cat­ing the looks of the round TC1 fil­ter as­sem­bly, by us­ing two Tri­umph Spit­fire 1500 chrome air fil­ters I was able to in­crease the depth over a stan­dard TC fil­ter by 20mm giv­ing a good 40% in­crease in breatha­bil­ity: an­other thing that the orig­i­nal TC suf­fered from! I started by dis­as­sem­bling both Tri­umph air fil­ter as­sem­blies and dis­card­ing the rear covers. One of the front covers would be utilised to make a new rear cover. The new rear cover was firstly and se­curely

screwed to a block of wood to make a more se­cure hold while I was work­ing on it. Af­ter draw­ing a cir­cle (slightly off cen­tre) I then chain drilled along the line and cut the piece out with tin snips. Af­ter that I used a burr in my drill stand and fin­ished the 65mm hole nice and smooth un­til the sec­tion of 65mm plas­tic drain spout would just slide in nicely. The in­ner di­am­e­ter of the 65mm drain spout­ing slides per­fectly over the in­let throat of the Mikuni HSR car­bu­ret­tor and was ideal for the job. Next I cut the drain spout­ing to give a to­tal length of 30mm, then slid it in the 75mm hole un­til it butted up on the in­side face of the cover. I then fixed the drain spout­ing in po­si­tion with in­dus­trial strength two-pack epoxy ad­he­sive. That con­cluded the work on the covers. Af­ter that, I cut two lengths of stain­less steel ma­trix mesh 50mm wide. One length was to suit the outer cir­cum­fer­ence of the cover, and the other to suit the smaller cir­cum­fer­ence slightly big­ger than the in­let throat of the Mikuni HSR car­bu­ret­tor. I also spun up two 50mm alu­minium spac­ers (with 6mm ID holes) and these would sit be­tween the in­ner faces of the two covers to stop them com­press­ing to­gether. The fil­ter foam from the Tri­umph fil­ters also then got in­stalled and then all got bolted to­gether. Then it got fixed to the Mikuni HSR car­bu­ret­tor. Eight small cuts were then made to the drain spout­ing where it goes over the throat of the car­bu­ret­tor (to al­low some flex­i­bil­ity) and fi­nally a Ju­bilee clip clamped the spout­ing on the car­bu­ret­tor. Job done and a vast im­prove­ment over the orig­i­nal TC1 air fil­ter! Now it was on with the fuel tap. The orig­i­nal fuel tap was way past its ser­vice­able lim­i­ta­tions, seiz­ing no mat­ter how much strip­ping and lu­bri­cat­ing was car­ried out. A ‘high flow’ Pin­gel tap from the USA is a min­i­mum of £150 + ship­ping, and I sim­ply can’t jus­tify that kind of money: Zed Power here in the UK does a great replica Z1R fuel tap for the pal­try cost of just £42. Sorted! Join me next month!

6 7 6/ Sump painted, on and filled. 7/ Turbo had strange bodge in front of it. 8/ Waste-gate dump­valve comes apart. 9/ Carb was mucky! 8



5 4/ Damn! It wasn’t empty then? 5/ Si­mo­niz to per­fec­tion!

1 2 THE BUILD: 1/ Nick in the cylin­der head would need work. 2/ Sludge build up in bot­tom-end not good! 3/ Anti-surge flap fit­ted. 3

ABOVE: Not Chris’s bike – but you can see the beauty of the TC...

Will (right) with owner Chris.

BE­LOW: En­gi­neered air fil­ter looks fac­tory!

ABOVE: Mad as a box of frogs over 5000rpm...

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